For those interested. I got arround to repairing the Supra yesterday, and thought it prudent to test the repair before jumping to the conclusion it was repaired..

Turns out, there was a small leak, from the return hose on top of the engine, where the clamp belt (thingy) was no longer holding in the pressure due to the hose having warped over time. I couldn't see it, as the leak was right underneath. After turning on the car, the acrid smell of radiator fluid started to come out again and sure enough, there was the leak. Turned the car off, waited for it to cool, and replaced the pipe (85 or 95 can't remember which one) Magna bottom engine feed pipe cut to size for those interested. Works well, no problems. About an hour of various driving styles and no issues. Thermostat is still removed, and will keep it that way. No point in worrying about it now.