A BBC uses the same motor mounts as a SBC. The only things you would have to change is the carb to a BBC one and the exhaust and it only needs to be changed at the drop-down tubes from the manifolds. Carb wouldn't "need" to be changed, but you would be hindering the motor some. This is assuming you got the complete BBC, brackets, accessories and all. TBI version would really need a 454 PROM for best results.