Impreza trans will fit, 5 OR 6 speed, just make up some shafts and mounts, add the pedal box and 'graft-in' some speed sensors etc and you're done!!!
(Done one myself,(6-spd), took me around 3 weeks including waiting for the shafts to be made/resplined. Cheers on the Cafe's there......
HTH
Cheers
Sixpack Subaru-do a search, (again?), there is more info here I am sure!!