I've done two MR2 BEAMS swaps and I wouldn't recommend you buy that Celica and try to swap the engine into your SW20 unless you're ready to spend some proper money on it.
Aside from the fact that you can't tell anything about its condition, there are also a number of other things you'll need to do to get it running properly in an SW20 – like tracking down an original BEAMS MR2 OEM airbox and intake piping, having parts of the exhaust refabricated, and more. Finding some of those parts isn't easy (or cheap). In fact, the airboxes are almost impossible to find, and the engines don't idle properly with pod filters. Unless you're really good at wiring, you'll also have to spend several hundred dollars getting someone else to sort that for you. The BEAMS engine loom in the Celica isn't going to work in your MR2, and the loom on your ADM GT isn't suitable for the BEAMS engine either, unless it undergoes major surgery.
Much as I love BEAMS engines, if you don't want a bad case of OMG! 'bill shock'

, I'd recommend you rebuild your own motor. At least then you'll know what you're getting into – and getting at the end. If you really want to go BEAMS, save some more $$$ first or it could all become a much bigger headache than you're ready for!
The fact of life is, doing an engine swap properly isn't a cheap option.