198 what ? last 454 w block i did i used AFR cnc 225 heads they sprayed it and was running it to 9000 rpms.. i did not know this .. my numbers on a custom soild roller with PAC springs was a custom piston you can get a good ring pack with a 9.500 deck never lost a piston i used a 6.125 rod piston CH was good any thing under 1.125 CH i do not care much for