That's a 1/3 point, nevermind almost a half point.
The stock gasket is the MP thin gasket, not the .040 gasket.
Your example is also misleeding since '78 engine is more likely a 7.8-1 engine with the pistons so far down the hole, it'll echo. I know what my '79 looks like on the INSIDE...INSIDE...inside...inside...inside ...inside...inside
IF THAT IS A OPEN CHAMBER 318 HEAD JUST BY A SET OF 302'S OR 920S FROM THEM
302'S AND 920'S HAVE A CLOSED CHAMBER
302'S ARE SWILL PORT AND 920'S ARE A 1967 HEAD