HKS used to make the composite steel head gaskets. Don't know if they still do. There is another company that makes them, but I can't think of their name right now. The cool thing about them is that they are reusable and rebuildable, and even adjustable by adding or removing shims to raise or lower the compression ratio.
If you can't find one, I would just o-ring the block and bring to the track a few OEM Nissan gaskets. Even the GT motors still use OEM gaskets.
Hopefully you're not going to use head studs though as they make head R&R a pain in the ass.