will gtp heads have any valve/piston clearance problems with SO pistons?
Most likely you'll need valve reliefs.
like magic,,, if you click that button called search,,
then type in this very thread title,,"gtp heads",, the solutions are there.
http://www.foxtbirdcougarforums.com/search.php?searchid=210577
lots of info in my diy link as well above my sig
what are valve reliefs?
cuts in the pistons to allow the valves to travel out without hitting the pistons. Last thing you want is your piston nailing the valves!