The OEM intakes will suffice for now. You can bore the stockers to 28mm and it'll help a bit. Just wait to upgrade the manifold till you do carbs. That cub will be held back quite a bit but considering the circumstances, it'll still probably out run most of what's over there.
Plan on just taking it all the way down. That kind of metal in oil automatically means there is a major issue, and the cases have to be split. No cutting corners.
That's because Heim joints on trophy trucks are top of the line, and most of the common A Arm companies that used Heim joints are using stuff that is Ok at best. Nowhere near the same level of quality. (Hey I said MOST, not all)
Yes, 70-80 hp on those if everything else is there. At least you have realistic power expectations. Definitely some 35's, timing, good cool head, reeds, new clutch components, etc.
ASV lever, new cable, fresh clutch kit.
You can take it a bit further and use one of the lock up clutches. They allow much less spring pull and use weights under centrifugal force to apply the clamping pressure instead of really stuff springs.
You should really consider talkin to less people who know nothing. There are all kinds of guys riding J arms hard and going pretty big off the top of dunes. Look what JD does with his .
The same people who would say something like that are the same goons to use and abuse a bike to the point of breaking with ZERO maintainence.