There's several variables on the c/r, i.e., height and gasket thickness but 64cc would definitely be a step in the right direction. Couple that with larger valves and a longer runner and things will start to come alive. I would still caution against the cam you now have - even with some significant improvements in the heads you'll need a high stall speed for the Powerglide (unless you want to go with different rear end ratio..)

Keep us informed and we'll throw our two cents your way!

Glenn