Well I ran some big cams with 6 pack pistons 0 decked and .075 off 906 heads with a .039 gasket 263/271 @ .050 .597/.620 lift.

after that had to deepen the valve notches as we ended up with .110 off the heads 62.5 cc closed chamber is what they became. 12.2 to 1 needed 50% 110 and 50% 94.

so you have .033 extra to start and heads that could use a good milling.

I would look at the Edelbrock E 75 cc head!