3.31” Crankshafts

For ages, the HD 318-3 crank was the "go-to" for any serious performance build.
BUT, be aware of the fact that poly cranks (manufactured up to '66, '67 for our northern neighbors) have a crank flange with a smaller pocket for the convertor nose, and if you are running a '68 or later automatic transmission you'll need to have that pocket enlarged for the convertor to fit.
A lighter reciprocating assembly will not require addition of any Mallory metal, but would most likely require some metal to be removed from the counterweights to get it balanced.