I had a 68 442... The day I sold it i seen 3 on the highway heading home. Like gut punches with everyone that passed.
I'm building a destroked 400... Dart SHP block, callies rods and crank, CP pistons, Dart Aluminum pro series heads... etc... should be good for 650-700hp
I built a few myself... same with th400s. One can build a th350 to hold power. I used to machine the clutch drums for extra steel plates and friction pads then set the clearance a little tighter, modify the valve bodies, sprag, etc etc...