In that case, get one with an LSD rather than an open diff (optional on SZ non-turbos, standard on RZ twin-turbos), use the sites I mentioned, and happy camping.
As a project car the RZ presents better "stuff" for the money. Torsen limited-slip differential (this is an option in the SZ, rare to find fitted. The standard A01A diff is an open diff and reportedly rubbish), 6-speed Getrag V160/161 manual as opposed to 5-speed W58 (V160/161 is a considerably stronger gearbox), thicker swaybars and bigger brakes.
Middle-ground is a late-model SZ-R, which the LSD was an option but was usually fitted, and it came with the V161 6-speed manual.
For the love of God though, don't indulge the whole F&F thing too much....another ruined Supra would just be a tragedy
There's a few Supra owners here on the forum, whom I'm hoping have build threads or similar. Take a look
EDIT: Something like this here would be a real treat.
6-speed SZ-R with the Torsen LSD, 107,000km, and most importantly a stock body!