engine mounts, transmission will hook up probably no problem.. might need a different flywheel... i remember the people who installed mine had trouble finding the flywheel for whatever (maybe that was due to me having a Turbo 375.. ) oh, and you'll need a new fan shroud.. i might have missed somethin else..
it MAY not be the same for fullsizes, but i believe it is, since 455's were an option. all you have to do is find a set of frame pads for a 455 and bolt them to the correct holes in the front crossmember. then the 455 mounts will bolt right up.
Big car mounts are the same. The frame pads are different. The only difference in the mounts is GS's have one hole for the pin, big cars have two. This is a photo of an Electra mount.