I put myself in a position to find out top end on 59 gmc,235 3 on the tree,390 or 410 gears with 7:00 16 tires.it did about 80 mph,but coming off a hill i heard a loud pop and motor wasnt running well.that move coused me to find a piston without a hole in it and instal.maybe was askin for to much,hmmm
