Make sure the clutch is adjusted properly (freeplay) and no air in the system. I recently rebuilt my master cylinder because it was leaking into the passenger compartment. Not much shifting improvement until I replaced the slave cylinder with a new one and adjusted the pedal freeplay properly. Here is a link to a eBay dealer that sells these and other Supra parts.
http://motors.shop.ebay.com/eastpart...911.m270.l1313
I used a one-man ball check type bleeder kit. About 4-5 pedal pumps between above normal reservoir refills or it will draw more air into the system. I could pump the pedal with my right arm and watch for bubbles in the clear hose under the car. I could also check the clutch fork movement with my left hand with the inspection cover off after bleeding. That is also a good time to grease the clutch fork contact points. It pulls right out in a turbo car, especially with the slave cylinder off. If you are going to replace the slave cylinder, soak the flare nut in penetrating fluid. I use a cotton ball or a small wad of paper towel to apply it and wait a while. A 10mm flarenut wrench is best or a very tight fitting 10mm open end. Those flare nuts round over easily.