Try a Cadillac 500. It's only slightly bigger and a little heavier than a SBC; it's got 150 cubic inches more displacement, and all the BOP transmissions bolt on- - - - -TH 350, TH 400, etc. and the 700R4 can be adapted easily if somebody really wants to deal with throttle linkage headaches just to have an overdrive gear. Those engines have enough torque just off idle to turn a driveshaft into a corkscrew if the tires get a good bite. Old Cadillacs aren't all that scarce, either, and there's a fair amount of go-fast stuff available if a stock engine doesn't float your boat.
There's also a good selection of 455 engines- - - - -Buick, Olds, and Pontiac all had them, and they're not the same engine- - - - -three different ones to pick from!
Jerry
