Here is the build when I put a 440 ROTAX into my Pilot
http://www.pilotodyssey.com/new440.htmPlan your work work your plan....
I chose to use the same clutch I was using with the Honda
Engine so before I removed the Honda Engine I captured the center to center distance between the crank shaft and the input shaft of the transmission I also captured the offset so when I installed my new Engine it was exactly in the same spot as my Honda Engine I also made sure it was plumb level and square with the transmission.
Now any drive clutch that was designed to work with a Pilot Engine will work on my setup, not really sure what I would do if I went to a OEM clutch since most likely the diameter will be different, a snowmobile clutch the belts are usually wider than a Pilot belt, doubt the offset will be correct.
108 clutch is fully adjustable just like the 102c and the 94c,
power bloc etc.
What exactly is the problem with your clutching?