I think I was running 17/38 on the it, you got the 4 speed? you can drop the it 5 speed traany stright in if you can find one. also look into having the head recut by one of the old school engine builders, they big yammies had bad pinging and detonation problems in high gear under load, reshapping the head fixed it right up. you will like the 5 speed tranny if you can find one
couple more tricks get an aftermartket antivibe stem, then replace the urethane parts with real rubber, and a caulk tube full of silicon sealer and fill the bars with it