Has the head or block ever been milled? Might not be straight.
Even if straight, something as small as not counter-sinking the bolt holes to prevent thread pull-up (or shortening the bolts) will blow the gasket.
Was the water circulation path tampered with? Block filled?
What's the actual bore size?
Not that familiar with the Fisher, but the pictures I have show an open chamber, vertical valves, with no quench - a flat piston would have knocking and turbulence problems.
That's really small for a cam, how identified as Isky?
Nothing available in a rocker.
What carb for the Eaton, mounted how?
