You can use a modern slipper clutch on the old Pantah drive train, but you will need to use a different actuator mechanism since the clutch push rod doesn't come from the left side of the case.
Redfox sells a set up ready to go but it is not cheap. If your handy, you could also fabricate one if you like.
http://www.redfox-grinta.com/cheers,
Tom