One guy on here put FR-S seats in his, not sure where the link is but it was pretty sweet looking. He said he had to modify the slides but it didn't look like it was too bad. A friend of mine put 300zx seats in his 240 and mine had seats from an earlier model one.
Celica seats may be a close fits and I drove my celica on thousand mile road trips with good comfort. Relatively.
You can put whatever seats in there that your little heart desires, but you'll be sacrificing the seat airbags and you'll need a pretty good drill. I mounted new day racing seats in my old 71 Camaro. After I did that, I realized just about anything is possible.