440 build for a tow rig/"muscle" truck?

sorry, my 76 with stacks is a short step side,its a d100 1/2 ton,2wd,tried 3.23s and didnt like the rpm my stall was too loose at hiway speeds, i cruise at 83mph on interstate, 3.55s and 46rh lock up would be perfect for my combination,my combination is makeing some good torque at around 2000 rpm,have to remember its a truck,its heavy,i use to have a 671 on it,was fun,i have two supercharged and a turbo car,this is just a fun truck,