I've been working on my big block install. Much to my surprise, stock 454 manifolds fit very well. The engine went in with no modifications to my car what so ever. I used stock small block frame mounts, and stock big block engine mounts. Since my car never had a/c, no mods were needed there either. If tall valve covers were used they would have hit. hood clearance is great, I have about 2 inches to spare. This is probably the easiest engine swap I have ever done. I do need to open up my rear end, something in there is locked up. Other than that, once tranny is installed, it will be ready to drive.