head gasket thickness??

sounds lot like my deal, motor outta a 85 diplomat runs like a top and didnt use oil! gonna get started home porting these 302s on it and get bigger valves installed. its a roller motor so i got a deal on a ...hate say it out loud mutha thumper roller cam and a street domonator intake holley 650 mechanical secondary's duel line, headers 2800 stall! need a rear end wanting 4:10 or lower gears then thin this duster down to meth head weight!! finding pistons a bit aggravating less ya buy a stroker kit witch id do but ant in the budget and heads already limited...but its what i got so going with it!