I have been thinking of replacing my 307 with a 350 but a friend at a car show Saturday made me an offer on a '90 454 out of a motor home he just acquired. I have 2 questions. First, this 454 is otu of a 1990 motor complete with serpentine blet system but it has a quadrajet on it. I figured 90 would be EFI.

My main question is this: My car is a '72 with A/C and a 307 stock. Would I have to get a different heat core housing for the big block to fit? I know i would have to get different motor mounts but what else would i need? My main concern is the hear core housing.

thanks for your help.

No change needed to the heater core or housing. Use 307 engine mounts on the big block if you want to keep your 307 frame stands. 350/454 engine mounts will NOT fit your 307 frame stands, so unless you plan on swapping them make sure you get 307 engine mounts. No difference in engine placement as long as the mounts are used in sets, 307 engine mounts with 307 frame stands or 350/454 engine mounts with 350/454 frame stands. Use a poly or solid mount on the drivers side mount only to keep from breaking a mount with either set.