He needs pistons more than anything, the slugs are down in the hole .100". Decking the block .060" to get it to within .020" of the deck is not the answer and probably not even physically possible.
If you are taking the rotating assembly out and decking the block then you're buying different pistons, case closed. He does not want to take the short block apart, just wants to see if smaller chamber heads will help performance. I maintain heads won't do much in this case, aluminum or otherwise.
He would be better off with a milder cam which does not require re-doing the whole short block. He can keep the lo-po pistons but could see an increase in cylinder pressure with shorter duration, like a step or two up from an RV cam.