I'm using the RPS Max street and RPS flywheel setup (now SpecialtyZ):
http://specialtyz.com/shop/default/sz-sport-street-for-vg30dett-and-vq35s-242.html
http://specialtyz.com/shop/default/sz-flywheel-vg30de-tt.html
Smooth take up, heavier pedal feel than stock, but not so much as to be tiring. Flywheel has rebuildable facing.
You should also consider replacing the stock pressed steel pivot fork with updated cast iron pivot fork:
http://specialtyz.com/shop/default/300zx/clutch-flywheel/300zx-heavy-duty-clutch-fork-kit.html
JoelyP is using the later version which has a lighter feel to the pedal than my version:
http://www.300zx.co.uk/forums/showthread.php?182696-Clutch&p=1886818&viewfull=1#post1886818