i looked in those indexes and didn't see anything mentioning iron fist 8. in fact, the MTU index contradicts the current order. for MTU 39, Spidey's last appearance is listed as HTD 1, not IF 8. furthermore, it states in the MTU 39 entry:
This story is said to take place on a Friday in August. This accords well with the date of Betty Brant and Ned Leeds's wedding, given as August 27 in AMAZING SPIDER-MAN #143. Inasmuch as this story takes place shortly before the story in AMAZING SPIDER-MAN #154 (which has the Sandman's next appearance after MARVEL TEAM-UP #40 and follows the story in AMAZING SPIDER-MAN #153 by about a day), the stories in this issue and the next must occur between AMAZING SPIDER-MAN #152 and 153. August is two or three months after the story in AMAZING SPIDER-MAN #152, well into Peter Parker's summer vacation, and it is almost certain that Peter begins his summer vacation with the trip to Cleveland to meet Howard the Duck in HOWARD THE DUCK #1. Therefore Spider-Man's appearances between AMAZING SPIDER-MAN #152 and 157 take place in the following chronological order:
HOWARD THE DUCK #1. J. Jonah Jameson sends Peter Parker on a trip to Cleveland on a Daily Bugle assignment to obtain photographs of a "duck that talks like a man." Peter is not seen asking for a leave of absence from classes, so the trip probably occurs sometime during Peter's summer vacation.
MARVEL TEAM-UP #39 and 40. "August" here means "early August," no doubt.
AMAZING SPIDER-MAN #153. The Homecoming Dance seen in this story has to be a topical reference. Homecoming celebrations take place in late September or early October, at the start of the school athletic season. Since it is known that MARVEL TEAM-UP #40 precedes AMAZING SPIDER-MAN #154, and the latter precedes Ned and Betty's wedding in AMAZING SPIDER-MAN #165, the story in AMAZING SPIDER-MAN #153 must also take place in August. The Homecoming Dance is probably connected with a class reunion and not a true homecoming dance. Such reunions generally take place during summer vacations.
AMAZING SPIDER-MAN #154 and 155. These stories closely follow the story in AMAZING SPIDER-MAN #153 and tie up some of its loose ends.
AMAZING SPIDER-MAN #156. The Brant-Leeds wedding, on August 27.
in the spider-man index, the entry for ASM 152 also makes no mention of IF 8:
Spider-Man and the Human Torch battle the second Big Man, the second Crime-Master, Fancy Dan, Montana, and the Sandman in MARVEL TEAM-UP #39 shortly after this story. They are joined by the Sons of the Tiger in MARVEL TEAM-UP #40.
as for specific reasons why the current order cannot work, we just have to take peter parker at his word. in ASM 153 he specifically says:
"yep, life would be just spiffy...if i could get a certain mary jane watson to talk to me! not that i really blame the lady, mind you. i just wish she'd give me a chance to apologize for...hey!"
shortly after, mary jane says to peter "no, little mary jane is just something to be brought to parties and ignored while you go galavanting around town snapping your precious 8x10 glossies! after what you did peter parker--i'd have to be out of me mind to let you talk to me!"
it's clear that she has not spoken to him since he ran out of the party in ASM 151. since they are seen together and, according to mj, "on a date" in IF 8, this cannot have happened between ASM 151 and when they made up in ASM 153. so, it cannot go where it is now if we're to take that conversation between pete and mj to mean anything.
where it should go is more debatable. there is no space in ASM 153 after they make up to insert IF 8, and ASM 154 is set "a few short hours later" - presumably that night. IF 8 could go there I guess, but since ASM 155 states that the events of ASM 154 happened "a few days" earlier, that seems like a more reasonable place to put it.