zex (comp cams) duel valve springs and steel retainers(no valve float)
stock GSR cams(no high lift)
forged H beam rods w/ arp 220,000 psi rod bolts(stronger)

Thy will help, 8500 is all I would take it but its your engine. Horse power drops off at high rpms du to the coil can not re charge and the injectors can only open so fast (you run lean). I would take it to a dyno and see what happens. At high rpms is wean bigger injectors, higher fuel pressure, distributor less ignition and a professional tune come into play do you have any of these things? What computer are you using? Thy all have different rev. limiters.

JE 9.2-1 forged pistons (thats with a type r head i think my compression is around 9.5-1 to 10-1)
What is your valve to piston clearance???
http://www.c-speedracing.com/howto/claymotor/clay.php
This is a big factor in rev