just get the yokes cut and swapped (make sure you get a box with a yoke in the end)
need a 33 clutch slave cylinder aswell...
but its all in one of these threads :S
its a LOT heavier than a 20 box thats for sure... if clutch is on the way out i'd look into that aswell.
had a few fiddley little probs with mine - like changing pivot balls etc but i think we just confused ourselves. should be box out, box in