if you are going st185, i'd recommend the following:
a) widebody = GT4A, any 92-93 models, RC. It's worth it having the factory widebody.
b) rev2 92-93 models. Any revision is an improvement. In this case, gearbox, shifter, clutch pedal box, larger front discs and switch from smaller 2pot calipers to large 1 pot calipers. I'm sure there are other things, but these are some of the revisions I have found as I've disassembled rev1 and rev2 celicas at pick a part. Revisions fix issues that became apparent after the first unit. Better to go with the latter. Aesthetic differences are also on the cars.
c) don't get a project. Get in something you can drive. Parts are available, but as with any project, parts can get harder to come by as the car gets older.
d) get the st205. They fixed everything wrong with st185s. You will be able to swap a reasonable amount over from 205 to 185, but the fun stuff isn't all transferable ie front brakes can't be transferred, but rear brakes can (with mod to stone shield), hub stubs are different, st20x brake booster unit swaps, but you have to use st20x MC etc etc
get this one if you're looking at TM gt4 1992
http://www.trademe.co.nz/motors/used-ca ... 826502.htm