I would recommend this one:
Comp cam number 20-230-4, lift .502/.511, duration @ 50 242
Even with pocket porting, the "J" heads will waste a camshaft with much over .500" lift. They are just not made to flow that much. right at or below .500" lift, they really shine. It's not always about flow. With the "J" and "X" heads it was more about velocity. The duration figures on the other two camshafts is really too much for what you have. That cam's duartion above is almost too much. 242 degrees is a heap. You have enough gear to compensate for it, though. I would stick with that smaller grind. You'll be much happier when you stab the gas. Just my opinion.