360 into 64

You didn't ask, but I assume you have thought about the transmission. If you keep your existing cable-shift one, pretty sure you will need an adapter ring to put over your smaller torque converter snout to fit in the larger hole in the 360 crank. The only alternative is to install a later torque converter, but I think that also requires changing the tranny's input shaft (must disassemble).

If you install a later tranny, you need a different drive-shaft, probably cut to fit. Would also have to figure a way to convert from its lever shift to your cable.