Wow, what a conversation with Steve at TEP. His first comment "...was, why, why, why would ANYONE use a P90A head when what you really want is an N42 or E88? You can't use anyother cam on that head." I did mention that it had been converted to mechanical adjusters. He suggested that then you have spend a lot of money getting the longer valves, tower spacers, etc. Then mentioned that "knuckleheads" do the .080 shave, made a reference to dumpster diver engine builders, and so on. So after about ten minutes of that, he told me he can do anything I want wrt pistons and cam. The only detail he mentioned was that he had the perfect grind for me at .490 and 284 duration. His JE pistons (he doesn't recommend anyone else's) are $1150 and a cam regrind (on a non-performance core) is $199. Interesting way to do business.
The only value I can see in using them is that as long as I provide accurate dimensional data, such as block height, rod length, bore size, etc., then the pistons I get will not have any interference with the valves - iow, valve reliefs, if needed will be added and only enough of a cut will be made to provide adequate clearance - keeping my CR where I want it. BTW, I called JE several days ago and they will sell their pistons at $150 each.