For drift or grip? The Falken RX7 is a D1 (drifting series) car so you probably won't be able to make a very good grip car out of it, lack of downforce and all. For drifting set-up, check the stickies in the drifting forum.
I'd suggest starting with this:
Ride height: middle rear, minus 10-20 up front
Springs: 10/8
Dampers: 7/5 (adjust bounce/rebound if you feel you need to)
Camber: 3/1
Stabiliser: 4/1
LSD: 1.5 way if you can, 20/40/10 if you have to use custom
Downforce: N/A
Tires: S for grip, N for drift
Brakes: 3/8
Aids: off
I have to admit I haven't tried these settings, but from experience they could work out as a good starting point. Personal preference plays a HUGE part in tuning, and IMO spring rates and dampers give the greatest effect.
If it's too understeery still, try lowering the rear springs (and dampers for more pronounced effect) in steps to around 5-6 and/or raise the front rate a bit. I never use dampers stiffer than 8 personally. If it's too oversteery, try evening out the front and rear settings.
If you like to ride curbs and bumps hard and the car doesn't, try reversing the stabiliser settings to 1/4 and/or lower the front dampers.