I'd say go with conventional and change the oil every race meet. There are plenty of synthetics without the friction modifiers but...the clutches on these things are pretty highly stressed who knows how they react to different oils.
Probably the best bet is to ask someone that runs them a lot.... I know a guy named Zack that rides one.
Your manual is 5 years older then mine. Its probably a little different. And after speaking with Rising Sun, Zack, and then Chris Marshall, I got different answers. All respectable answers but different. I took Chris's advise because he's a handsome Canadian.