These guys stuffed a 2JZ into a Honda S2000, so anything is possible.
http://www.drivingenthusiast.net/sec-blog/?p=5795
Make sure that
1) the engine will fit in the engine bay. The Toyota inline 6 is a long engine.
2) Plan on using the Toyota gearbox. Mating a Supra engine to a British gearbox sounds like a nightmare.
3) You'll be modifying a bunch of stuff, and custom fabricating the motor mounts and transmission mount as a bare minimum. Make friends with a good welder.
4) You'll need to find a place that can custom modify the driveshaft to fit.
5) Bone up on the Supra engine control system. You'll need to swap over the electronic controls if you wish this to work.