it's actually quite simple, E85 has the octane rating of race gas but isn't 10 bucks a gallon....to truly take advantage of it you need high compression and advanced timing or a turbo, but in this case I simply want to gain some experience with tuning a carb'd vehicle to use it, and also I could find a way to advance the timing even more later once the bike is running half decently.

the benefit of E85 is cost, if horsepower and detonation resistance were the only concerns you could run methanol or leaded race gasoline.

btw the whole "omg it's so corrosive and will destroy my fuel lines" is a common myth from people thinking E85/E100 is like methanol. Any vehicle that uses gasoline made in the last 20 years can use E85 without issue to seals and lines.