Good luck with the swap.
If you decided to try the ST202 SS2 (w/ super struts) Celica axles I mention in that last link, let me know if they work. I wanted to try those on my ST202, but I couldn't find anyone to import the parts for me. They are one piece from trans to hub, so you wouldn't have to mate MR2/Celica/Camry axles together.
Also, I've found the stock rear transmission mount to be pretty weak. I have a few mods to my 3S, and the amount of front-rear engine movement - even with new mounts - is horrible. I plan on replacing the rubber with urethane in the front and rear mounts.