Thanks for all the great suggestions guys. The plan is to pull the head and reinspect all the parts to see if there's a smoking gun. Hopefully I find something apparent. If not the new fiber gasket goes in and we see what happens. I'll keep you all posted....

Sort of stock 1950 Chevrolet 3100
235 (The engine shread) (Engine assembly)- 4 speed - 12 bolt - stock front axle with power disc brakes