Balancing is going to cost 2-3 times grinding a crank. If you are not racing, then changing pistons to oversize does not necessitate a re-balance. So haw hard are you going to be running this engine?
Just be aware: Since both the 273 and 5.2 are 'internal balance' engines, there is no need to balance the crank with the external parts. Each of those external parts are individually balanced.
