Pushrod Length for Shaved Heads

It depends. If you somehow plan on taking advantage of the quench the closed chamber head can give, then no, IMO, the 452s would not do it. If your plan is to leave the pistons in the hole at TDC, then the 452s would be the better choice.
I would say for now the pistons will remain as is, which is about a mile down the hole. Someday something better, just trying to get it together and finish building the car. Then works new build bugs and maybe build something better.