Which heads to run on 340

I see i just thought the J heads had a larger CC combustion chamber but i could be wrong i know the 318 heads have a smaller CC combustion chamber. Ill probably just end up using the J heads now and punch the valves to 2.02 i got a guy that does it pretty cheap and hes really good hes slower but he does really good work. Then gasket match, clean the bowls up and slight milling. This would make a pretty good head to run correct?