Originally Posted by silent noise
Shut up stupid.
To the original poster, use a p72 head. There are many IM that you can use, it's all preference. Pick up something like a 98+ JDM ITR header. Golden Eagle has a kit along with many others. If you have the funds, swap some new pistons and rods in, something like 11:1 CR. Throw a new valvetrain in with a CTR Intake cam. You'll have a fun little motor.
True. A P72 will bump up your compression and AEBS, Blox, Wicked Industries, and Skunk 2 all make IM for the GSR head. As far as Pistons go, if you want extreme you can use CTR pistons(with CTR's you have to machine either the rod or the piston 1mm to make fit) for really high compression or P30(JDM B16; will fit with no machining) for a lil bump in Compression. Also I recommend shotpeening the rods and use ARP 8mm rod bolts since you will more than likely take the motor over 7400 rpms.