I just got done putting a 454 in my 87, the mount location should be the same as if you were swapping a small block. I used the forward most holes, which caused one of the four bolt holes to hang over the edge. I got some coated shorty headers for a mid 70's camaro and they worked fine. From the looks of it I thought I might have to ding them in a couple spots, but it worked out fine. You might also have some clearance issues w/ the oil pan, depending on if your gonna use the stock one or not. You might also have to whack the floorpan where it forms into the tranny tunnel for extra header clearance. And also depending on what distributor you use you may have some clearance issues with the wiper arm, I used a short profile msd billet and it cleared great. I also know some who use original hei units no prob. Also if your gonna use a mechanical fuel pump, keep in mind the lines are on the other side...other than all that, pretty simple, drops right in
HTH
Tony