Fit into truck: Yes, it will fit. It will fit into anything, MG's, Corvette's...trucks have plenty of room. Distance from motor mount to trans is the same SMC/BBC. The extra length is in front of mounts. Same motor mounts will work, may have to use low style valve covers.
Tranny fit: Everything fits everything from about 62 on. So if you have a 350 then, yes, tranny fits 454.
This is why Chevy drivetrains are so popular and easy to work with. There is nothing like the sound of a BBC. It vibrates your diaphragm the same as a Harley.
454's have peanut port heads and oval port heads. Try not to get peanut. Rectangular will be hard to get and not for daily drivers. Google all that to learn.
