Over the years I’ve seen several 340 A bodies soundly thrash 383 B bodies. It seemed they always got them off the line and the big block couldn’t run them down.
lol The first engine I put in my 67 fastback was a 68 383 magnum with hp manifolds, with matching convertor and torqueflite. that combo and a 4.57 sure grip was unbeatable by any stock a-body 340. lol
a couple years later the 383 got 12.1 comp , ported 906, 557 purple, street dominator / Carter AVS and hooker fenderwell 2" primary. lol I forget what convertor we put in, but that combo was beast. lol