225 slant 6 or 360 v8

I'll say a stock 360 mag will get ya into the 13's with highway gears. Schumacher makes adapting motor mounts for 150.00 bucks, no need to change the K frame. New radiator, tranny, exhaust, motor mounts. Then, whatever you decide for the motor. Shoot, a stock 318 mag will get ya 14's with ease.