JE makes custom pistons, so you may want to talk to them. Might wanna check out
http://www.sgpracing.com/ GQ_626 just had a group-buy on Arias pistons. The pauter forged rods SGP Racing sells look twice as strong as the stock one's. AEBS also has a stroker kit with all new internals, may want to check them out, it strokes the motor to a 4.3, and you can get the compression in 8.5:1.
There aren't a lot of options right now but you should start seeing things pick up. Ferrea makes awesome valve kits, I don't think there are any for the Z yet though. JUN makes good internals also. Hope this helps.