It is not a big deal at all. I just dropped my 427 into my 88 IROC yesterday.
I did remove the ac heater box.
The car still has power brakes. I am running large cast aluminum valve covers. The wiper motor needs to be modified to clear them, but thats it.
Headers, you can get hooker super comps (what I have) or Ed Quays.
I am running a B&B drag pan, and it fits with no mods. Stock crossmember and all.
I am running a Victor 454 O intake with a 1050 dominator. It clears my small cowl hood well.
I can show you some pics if you want.
Oh, I used the stock motor mounts, and they fit great!
I am using a small cap dist. and I was almost able to get it in without even taking the cap off.
This motor fits a lot easyier than the 427 in our 1955 Belair.