I don't believe the angle affects anything, that is the only question I had. The engine runs smooth and seemingly normal. My first three tanks of gas gave me this result, 182,178 and 184 mpg.
A counterweight is absolutely unnecessary as with such a low center of gravity, it is unnoticeable. I did have to cut the kickstand shorter to avoid a guaranteed tip over.
I forgot to add... maybe a piece of sheet metal under the engine to act as a skid plate ... better wear marks/scrapes on a 5$ piece of metal than your engine 8) 8) 8)