How about this, it might work. a 1979-1981 267 SB is the same bore as a 350, maby a 267 with a 283 crank, it would make it smaller than original but would wind up quick. I don't know if you can mix the 283 crank with the 267. Another option is to fit a 400 crank in it, that would make a stroker, you'd end up with like a 302 in the end with the 400 crank.