I have a 5 speed out of a KE70 in mine, the only modification needed is the hole in the floor cut further back towards the driver.
From what I have heard, the KE3x - 5x style even in 5 speed still don't fit the original floor hole. If you are going to all the trouble of making this work I suggest you get a KE70 style, as it puts the shifter in a better position for driving too.
Clutch and pressure plate are the same for 4 and 5 speed.
As for the tailshaft and crossmember woes, I am guessing like all Rollas there is a difference between manual and auto unfortunately :)