There were 3 FX's. FX, FX16, FX16-GTS. Since you said ITB, I'm assuming you have an FX16. The base FX had a carbed SOHC engine and an el-cheapo interior; the FX16 had the L-jetronic injected 4AG twin cam engine and an upgraded interior; the GTS was mostly an appearance package (better seats, aero package). Functionally, the FX16 and GTS are the same car. Properly built, you can get about 110 wheel HP out of it, and it should be very competitive (IMHO) in ITB.

Suspension settings? I'd start with about 2* negative camber on both ends and about 1/16" of toe - out on the front and in on the rear.

I race its "backward" cousin - an MR2. FWIW, it's the same drivetrain with the shifter arms reversed in the transmission housing and a different header. Your biggest problem will be finding decent brake pads - and you'll need them, especially on the front. If you are really lucky, you may stumble on to a modded transaxle for an AW11 MR2 or an AE82 / 92 / 101 Corolla - with a LSD and a 4.73 final drive. You can take the guts out of the diff and put them in the FX.