Call Ross, that may not be a custom piston, they will do changes to a shelf piston for a small cost, which saves money and time. I needed a 4.50 bore for a 4.25 crank which was not a shelf piston, they took a 4.5 stroke piston and just machined the compression height to fit my needs. They also gave me an order number and let me buy my pistons through summit and that saved me $100.00 after their tech guy and I went over the measurements.