1973 340 detuned?

I'm doing rebuild on my 72 340 now. I did cc of my head chambers and they went 70-72 cc. Easy to check by setting a CD disc on head w grease to seal edges. Then inject alcohol in it w syringe. I picked a set of speed pro forged pistons L2316F with cd height of 1.840. For my block, heads, gasket should yield 9.5 CR.