Shaved heads and head gasket thickness.

The felpro 8553 are are pretty thick i believe they are around .054 before they are compressed they seal very well too. And btw rock auto had them on sale for pretty cheap last time I looked . You can buy custom cometic gaskets up to like .120 thick but they are very expensive they are like 215 each!

Something key to know and state.. is what cid engine and what fasteners did you use?
318/273 use less torque on the heads and fasteners can play a part in heat cycled clamping force. So less torque, less clamp, less clamp, less crush...
The same gasket used on a 360 crushed @.046 ,stock heat cycled bolts.
There's 10 lbs diff between 318 &340/360LA and even more for magnums, 114 or something near. So in order to give useful advice we need to add a description tag to our contributions of what and where and how
CID? Fastener?