Inliners International Forums General Discussion Hi Performance 250 Zero deck question

Leo's book pg30 recommends max .030" decking.
The deck on my stock engines I have handy are, with the engine codes:
292 stock bore THR .032 deck
292 30-over THH .023 deck
250 stock bore TAX .027 deck
AFAIK these blocks have not been decked but I couldnt guarantee that.

So at least for me .040" deck clearance would be a lot.
I wonder, is there a thinner head gasket to use? Do they seal?
Some of the steel shims are only about .020" thick and it is the total quench clearance that matters, so 0-deck with a .040" gasket would be the same as .020" deck and a .020" gasket -