When this story was examined it was dismissed, a bit too fast in my opinion. The story is treated as canon in the Marvel fandom wiki. I address here what objections have been formulated earlier regarding Dr Strange, vampires, Iron Man's armour, Diamondback, Nick Fury & Strucker.
In ST2 3/2 Strange makes Sara and Wong forget about him. It turns his sanctum sanctorum into the Stephen Strange Memorial Metaphysical Institute and makes Wong and Sara see him as a Dr Sanders. Strange lifts the spell for them in ST2 17/2 (Aug 88). In ST2 14/2 (May 88) the FF saw Strange fight Shuma-Gorath. DSSS 1 reveals the spell's particulars: Strange was believed dead fighting the Beyonder and a video exists of his burial by superheroes (incl. Captain America) and mystics. However by this time, the information that he's alive might already have reached the Avengers through the Fantastic Four's report on witnessing his fight vs Shuma-Gorath in FF 314/ST2 14/2. In CA 355 Cap says Strange is "believed dead," which paradoxically points to him knowing he is alive, otherwise he'd just say that he's dead. By the time of Inferno (A 298-300, Dec 88-Feb 89), the spell is still active for civilians (X-Factor Annual 4/3) so it is expected Cap would say "believed dead" even if he knew otherwise.
It requires moving ST2 14/2 for Druid and therefore FF 316 (Jul 88) since FF 314 is concurrent with ST2 14/2 and FF 314-316 occur in succession.
Cap gets his vibranium shield in 342, which is also when Diamondback becomes an ally as she calls Cap's hotline for help during Viper's violent takeover of the Serpent Society. In 344 he tells her what to do to earn his trust and she complies.
The presence of Strucker is easily explained. During the time of Strucker's death, LMDs of him appeared in CA 130-132, CA 247-248, 273-274, X&AF2 1-2. This Strucker is only "Chief of Special Operations for Hydra" rather than Supreme Hydra so he's not the real one.
By CA 351 (Mar 89) SHIELD has just disbanded so wherever CA:HH 4 occurs between CA 342 (Jun 88) and CA 349 (Jan 89), nothing prevents Fury from being Director of SHIELD during the Captain era. NFV.SHIELD 1-6 was published Jun-Nov 88 and Fury & SHIELD last appeared before this in IH2 346 (Aug 88).
Iron Man creates a new red and gold armour in IM 231 (Jun 88). His appearance in CA 341 (May 88) occurs just before the destruction of the red and white armour. In CA:HH 4 we see the classic armour, either this is an artist error or this is before the new armor is completed in IM 231. I chose the latter option and placed the story in the weeks-long break during which he builds the new armour (on the conceit he used parts that were ready and completed them with the older design when the emergency arose, then resumed his work with the new design).
CA 341 (IM in Silver Centurion armor)> IM 230 (armor destroyed) > ST2 14=FF 314 (FF see Dr. Strange alive) > FF 316 (FF contact Dr Druid) > A 293 > WCA 36 > CA 342-344 (Diamondback allies with Cap and D-Man) > ST2 17 (Strange partly lifts spell for allies) > M/CP 2/4 > IM 231 (first half, no IM armor exists) > CA 345-346 (Cap in jail) > IM 231-234 (new IM armor) > WOSM 42 > NFV.SHIELD 2 (Avengers and WCA informed Fury is fugitive) > XF 32 (Avengers) > NFV.SHIELD 3-4 (Stark) > WCA 37-39 > A 295-297 (Avengers disband) > CA 347-348 (Cap freed) > A 298 > A@ 17 > CA 349 (D-Man lost at sea) > A 299-300 > CA 350-351 (Cap finds out SHIELD has disbanded)
The existence of vampires is a minor point. Maybe they're false vampires, like Bloodsport in Wolverine #4, published around that time. The existence of the specific name "Red Immortals" points to a special breed anyway.
With all those objections lifted, only remains the task of finding a break for the Captain, Falcon, D-Man and Diamondback. This should be after cooperating with Diamondback vs Viper in 342-44 (Jun-Aug 88) so that she acquires enough of an ally status to show up with the heroes in CA:HH 4. There is a break of two days between pages 21 & 22 of 344 but D-Man and Diamondback are prisoners by this time.
On page 11 of 345 (Sep 88), Sidewinder frees Nomad and Diamondback and leaves Vagabond in the prison with D-Man. But in the next issue D-Man is alone in prison. Sidewinder must have returned to free Vagabond. And, we shall assume, D-Man as well so that CA:HH 4 can take place here, with D-Man being captured again or voluntarily turning himelf over (just like his role model, the Captain, decides to do on page 13).
BARON STRUCKER
M/U 3
*CA:HH 1 add
NFAOS3 3-FB
NFAOS3 4-FB
NFAOS3 5-FB
WX2 14-FB
...
*CA:HH 2 add
ST 150
BARON STRUCKER LMD II
X&AF2 1 | cf ALL NEW OFFICIAL HANDBOOK 1
X&AF2 2
*CA:HH 4 add
CAPTAIN AMERICA/STEVE ROGERS
CA 342
CA 343
CA 344
CA 345-FB
M/CP 2/4
CA 345 (1 - 11)
*CA:HH 4 add
CA 345 (12 - 22)
CA 347
CA 348
A 298
A@ 17 Evolutionary War
CA 349
A 299
DEMOLITION MAN/DENNIS W. DUNPHY
CA 342
CA 343
CA 344
CA 345-FB
CA 345
*CA:HH 4 add
CA 346
CA 349
DIAMONDBACK II/RACHEL LEIGHTON
CA 342
CA 343
CA 344
CA 345-FB
CA 345
*CA:HH 4 add
X@ 13-FB
DOCTOR DRUID
A 294 (Aug 88)
*ST2 14/2 (May 88) move to here
*FF 316-BTS (Jul 88) move here
CA 343-BTS (Jul 88)
CA 344-BTS (Aug 88)
*CA:HH 4 add
WOSM 42 (Sep 88)
WOSM 42-FB
NFV.SHIELD 2 (Jul 88)
XF 32 (Sep 88)
*ST2 14/2 move from here
*FF 316-BTS move from here
WCA2 39-BTS (Dec 88)
A 295 (Sep 88)
A 296
A 297 (leaves Avengers)
DOCTOR PYM
A 293
SOLOA 8/2
WCA2 33
WCA2 34
WCA2 35 (1 - 17)
WCA2 35-FB
WCA2 35 (18 - 22)
WCA2 36
*WCA2 37 move from here
CA 344-BTS
*CA:HH 4 add
*WCA2 37 move to here
WOSM 46
SOLOA 16-FB
DOCTOR STRANGE/STEPHEN STRANGE
ST2 14/2 ~ FF 314 (May 88) Dr Druid, FF see Strange vs Shuma-Gorath
ST2 15/2
ST2 16/2
ST2 17/2 (Aug 88) lift spells (from ST2 3/2) for Sara & Wong
*CA:HH 4 add
ST2 18/2
ST2 19/2
DSSS 1
DSSS 2
XF@ 4/3-BTS Inferno
DSSS 3
DSSS 4
M/CP 19/3
M/CP 20/3
FALCON/SAM WILSON
SOLOA 6/2
CA 342
CA 343
CA 345
*CA:HH 4 add
A@ 17
CA 349-BTS
FURY, COL. NICHOLAS "NICK" JOSEPH
IH2 346
*CA:HH 4 add
NFV.SHIELD 1
NFV.SHIELD 2
NFV.SHIELD 3
NFV.SHIELD 4
NFV.SHIELD 5
NFV.SHIELD 6
CA 351 (1 - 15)
GEIST, NIKOLAUS
W2 19 (19:2)-FB
X:TF 1
X:TF 2
X:TF 3
*CA&N 635.1 add
*CA:HH 1 add
W2 19 (19:3)-FB
W2 19 (19:4)-FB
A1959 5
*CA:HH 2 add
*CA:HH 3 add
*CA:HH 4 add
W2 18-FB
{W2 17}
W2 18
W2 19
W2 20
W2 21
W2 22
W2 23
*CA:HH 5 add
GIANT-MAN/BILL FOSTER
A 246
*CA:HH 4 add
WCA@ 3 Evolutionary War
WCA@ 3/2
WCA2 39
HAWKEYE/CLINT BARTON
WCA2 36
*CA:HH 4 add
NFV.SHIELD 2
WCA2 37
SOLOA 10
SOLOA 11
WCA@ 3
IRON MAN/Tony Stark
CA 341
IM 230
IM 231-FB
IM 231 (1 - 12) break here
*CA:HH 4 add
IM 231 (13 - 23) new armor
BICM/W 1/3
WARM 1 (7:3)-FB
IM 232
IM 233
IM 234
[[[CLICK & DRAG: alternate *CA:HH 4 add]]]
XF 32
NFV.SHIELD 3
NFV.SHIELD 4-BTS
IM 235
IM 236
MOCKINGBIRD/DR. BARBARA "BOBBI" MORSE
WCA2 36
*CA:HH 4 add
NFV.SHIELD 2
WCA2 37
WCA2 3/2 -> WCA@ 3/2
WCA2 39
MOON KNIGHT/MARC SPECTOR
WCA2 36
*CA:HH 4 add
NFV.SHIELD 2
WCA2 37
WCA@ 3/2
WCA2 39
SHE-HULK
A 294
*FF 316-BTS move here
*CA:HH 4 add
NFV.SHIELD 2
XF 32
*FF 316-BTS move from here
A 295
A 296
A 297
THOR
A 294
*FF 316-BTS move here
*CA:HH 4 add
NFV.SHIELD 2
XF 32
*FF 316-BTS move from here
A 295
A 296
A 297
TIGRA/GREER NELSON
WCA2 36
*CA:HH 4 add
WCA2 37
WCA@ 3/2
WCA2 39
WONDER MAN/SIMON WILLIAMS
WCA2 36
*CA:HH 4 add
NFV.SHIELD 2
WCA2 37
WCA@ 3
WCA2 38
Post Fall of Mutants to Evolutionary War (indicative only, there are differences with listings):
Spoiler: