what ever you do don't replace the engine with anything other than an nailhead, If you didn't already know your tranny is probably a sp400 (not th400) which is a switch pitch transmission. When you nail it the torque converter switches it's stall higher then back down. You might want to join V8Buick ,they have alot of information to be had there. Also thoght you might like this
never liked pink but there's something about this one