I also think the 1UZ or 3UZ is a better idea than the 2GR, not that I have any experience with those engines. I do have experience with a GR engine in my 06' 4runner (4.0L 1GR-FE) and it has no where near the refinement (or sound) of a I6 like the 2JZ-GE in my 02' IS300. I've read that the 1UZ was one of the best engines in the world when it was developed, with the refinement on par with the likes of luxury manufacturers.
Also, another funny tidbit of info I've recently seen on FB and IG: A guy in Russia swapping out the GR engines for 3UZ-FE's into 2nd/3rd gen IS's.
02' MT w/MK3 Supra LSD and no sunroof