Anything's possible, I know guys have done it into S70s and V70s so search for that. I'm pretty sure the mounting is different but not radically different. Might require some welding but the seat frames are all mild steel which should be pretty easy to deal with. I'd say grab one junkyard P2 seat and strip the fabric to see what's what. Oh and the mounting changed in 2005 so if you specifically want R seats, pick up to 04 or 05 and beyond.
Also regular T5 sport seats are 99% the same as the R seats but have tougher less exotic leather. You'll also have exact color match options if you go that route. The R seats are exotic colors that won't match anything a C70 came with.