Where to find thin .030 or less head gaskets for 4.070 bore

Get ahold of Cometic. They will make you anything you want but they are not cheap. Keep in mind that you will need a minumum of .035 piston to head clearance, so if you are a building a stroker, you may as well have it decked for zero deck and use a .035 to .040 gasket.

Granted, some will go with a tighter quench, I personally know of someone who runs .028" P to H clearance, with H-Beam Carillo rods on a BB stroker and swears that at 7K rpm "the piston just kisses the head". This guy knows his stuff and this is not street and the engine gets torn down every season.