I had another USX owner install my Staton kit with Honda 50 engine.  He said that Staton machined him a left shaft.  If Staton does not have any extended shaft take your left shaft to a machine shop.  Remember you are only making the left shaft 1/2 inch longer and the end of shaft needs to be threaded for a spocket.  The thread on spocket was either left or right thread I forgot I am sorry.  Another way to extent original left shaft is to weld on extra threaded lenght.  I know of two owners who went this way.  One owner was completely satisfied and one hated his.  The shaft must be completely straight.  The more off center the shaft the more vibration.  Where ever you get the shaft done  check the shaft for straightness.  THE SHAFT MUST BE STRAIGHT!!!

Welding is the cheapest way.

Hope this helps.

 

Mike

Rocklin, Ca