We have one close to us that produces (alledgedly but I recon it prolly is) close to that figure, certainly its guestimated over the 1000hp anyway.
It doesnt run anywhere near those times best its ever ran is 9.9 but I have never seen it run close to that time, generally high to mid 10s.
To go from a 10 to a 7 second pass is some achievement, its a different world. For me personally the engine is fair doos but its the car thats making the difference. Lot of lightweight panels, rear tubbed end is just excellent and I will guess its still running a race auto box.
Never personally had any doubts about the Supra block being up to the job just was never convinced the Supra was the car to put it in

I am not a big fan of driving them, its like looking out of a letterbox and the car handles like a tank.
Now a Supra engine in a Lex, well thats a different story and it looks like a wining formula