as for clutch, alot of people used to use a holden 1 tonner.not sure of the 'how' tho. maybe you should check out what's available for hi-ace/hi-lux in heavy duty type arrangements. The b/housings were interchangeable to suit different engines.
BTW friend of mine was running a "steel case celica" read W50. behind a twin turbo v8 celica. I think there's a few pics of it here at toymods somewhere. Note tho' this car did'nt weigh very much either, which makes a difference to box and clutch life when combined with an aggressive driving style!!!