Ramcharger,
Comp made the custom cam for me. Just under $300.00 for the cam and needs a spring with 170 lbs. @ 1.550. My springs are 130 @ 1.62 and 300 open.
This is why gas port pistons are so popular in good bracket race engines. They use combustion gases and pressures to seal the top rings to the cylinder and pistons. But these rings are a good bit more money as are the pistons that use them.
IIRC, the KB hyperutectics I installed in my last 360 build had gas ports between the first and second rings. They were relatively reasonably priced too. Just food for thought.