Did they not offer a 454 in a 97? I can't remember but if they did then I'd think the caddy would be a fairly straight forward install with just the normal tweaks encountered. I'd check to see if big block parts may have given positioning that allowed fan, exhaust, etc., clearences. I don't know but it might be worth a check. Here is a picture of a 500 Cad in a 51 GMC that the firewall is stock.
http://s32.photobucket.com/albums/d41/coilover/ Scroll down to bottom of first page. It's been over 30 years but I think I used a Ford flathead six cylinder radiator that was mounted forward in the core support. Cooled great. Stay in contact with Oldsub because his views are from right now, not thirty years ago.
