New pistons in 68 318

273 pins have same OD as 318 pins but they are much thicker walled/weigh more to compensate for the 273's smaller piston with the same 318 balance of the poly motor the crank came from. Put 318/340 floater pins in the OEM 273 pistons and youll save weight. shop around and you can find wide range of balance pricing. I found a guy that will do crank only for $75 if I bring a balanced "across the board": piston, pin, rod, cap and ring pack. Thats to drill/lighten to balance, no tungsten. I have said HF 1kg digital scale and balanced everything to each other to .1g, Even the nuts. Pistons were hardest as some were really out of balance and I was looking for places to lighten so I ended up taking some off the pin ends as they were pressed by now. I think some of my pistons were 15g over weight of lightest one. Rods were tough, tried to balance little end on knife edge at parting line to scale but it was not repeatable so ended up getting them pretty close this way and then balancing the entire rod itself to all the others and then the caps to each other. Import engine builder said this was sufficient, although they usually deal with single plane cranks.