273 how far below deck are the stock pistons?

Ron R I'm gonna run it in time attack (solo 1) up on the road courses here in Ontario so gearing depends on which track I'm running but I imagine they all will be 4.56 + and yes I'm putting in a 4 gear. So for the road course I want a 2000-7000 powerband but got to stay around 400HP so I don't go in to high of a class and have to run with vipers with my 65 Cuda that's why I'm sticking with the 273 plus it's a challenge.