Brainstorming an Idea, whats your 2 cents

The pistons will need to be .420" shorter to be at the same spot as the ones you have now. You cannot mill more than .160. So even if your pistons are in .040 down, you are still too tall by just shy of 1/4". You either need to replace them, or replcae your carnk. FYI I have a 360 that needs a crank kit. I priced it at $175 for a crank and bearings with exchange. Your KBs are lighter than factory cast, so if yo simply swapped cranks, you would be overbalanced. That's not what I love to have, but it's better than being underbalanced. Plus, you could have the new crank spun and weight matched to the old crank. Then it's a drop in deal. The whole mess might cost $400. Add a light hone and new rings, and you're done for $600 or so...