<font color='#000000'>the infamous 3s-gte swap is what you're asking about, jhull will tell you everything you need to know about the swap for the fifth gen.
not so feasible to swap in a supra engine. although possible, it might be cheaper to just buy a supra intact:
1. not a cheap task
2. the supra engine is mounted longitudinally, the engine in your celi is mounted transversely, lots of work needs to be done to accomodate the 2jz
3. the supra engine's pretty big, you'd have to cut into the firewall of your celi to make it fit
4. not to mention, converting to rwd</font>