The T78 is way more topend, compared to the small little stock Z turbo's. He will catch you and crush you bad. Not the car, just to Hp rating it is at . It's also something that still is just not proven on the Z side. Supra's easy to work on, parts are cheaper ( single turbo ), there for many go the easy route and talk shit. Sad but true. I can post you about 25 video right now if you like of the Supra meet in TX. A 10sec car seems to be everywhere. Yet the good thing is, not all are good drivers :)
Also looking at your profile a T78 Supra has about twice to the wheels ( to the wheels ) than your car as it sits now and that's if it's running good. It's just not a good comparison at all I'm afraid.