Inliners International Forums General Discussion Engines What is the compression ratio?

I'm rebuilding a 1954 261 engine with a 1959 848 head and I've been told I should wind up with an engine of "about" a 9:1 compression ratio. I understand the concept (I think) in general terms but not much more. The changes to the engine are

.030 over Egge flathead pistons
head surface milled .003
block surface milled .003
crank bearings .010 / .010
valve sizes remain the same without porting done inside the cylinder head

My intent is to run higher than standard octane fuel, as needed to prevent knocking

Curiosity is driving me crazy, any help appreciated.

Ted