Is your car already a 5sp. or is it auto? If its already a 5 sp. stay with the R154. I there are a few changes that need to be made, but nothing that is a major issue. Talk to Phil Bradshaw, I think that he has an adapter to use the R154 and stock 1uz auto bellhousing.
Along with that, its easier to revert to the W58 style clutch being that it is a push style pressure plate where as the R154 used a pull style pressure plate. The clutch actuation is the easy part, no need for a fork or any thing of that nature. Just a particular Hydraulic release bearing that is pretty cheap from summit racing and just needs the bearing changed. Another easy task. I can fill you in on all that later if you do decide to go that route