Low vacuum question

sox and martin said
Seeing as you cut the heads, I would investigate lifter preload if you are using non adjustable rockers. You may have to use some shim stock to get about.020" lifter preload. If this is incorrect, vacuum and low end performance will suffer.

I am eventually going to replace the rocker arms with adjustable ones but correct me if I'm wrong right now I'd think that shouldn't be that much of a concern even though the heads were cut because the new head gaskets (Fel-pros) are .042 thick whereas the stock ones were steel shim type. I don't know the exact thickness of a stock type but I'm sure it was alot less than the Fel-pros so I'd think the .020 we shaved off the heads would be nearly compensated for by the new thicker gaskets.