don't worry about the head the stock stuff will work just fine. get the block sleeved by golden eagle and bore it to 83mm. get arais 83mm 9:1 compression pistons and the eagle High HP rod(good to 900hp). I really don't know about pushing a SC to 15psi I would avoid that kind of boost and if you want in the 500whp get a turbo kit. also I would get a hondata and 880cc or 1000cc injectors