440 crank in 383 block

As was said, counterweights need to be reduced in diameter and main journals turned down to B wedge size. As far as the amount removed... there is no surface hardening on factory RB cranks unless it's a 426 Hemi. However, it is a lot to be done to a factory crank. It is not cost efficient IMO. Best bet is the 440Source B wedge 3.75 stroke crank. Better part, stronger, heavier (which means easier to balance with the RB rods), and drop in.