Hi! I came across this build because I was searching for others who had used an OHV in vertical orientation the way you have. Great build!
I'm about to start my first, using the same or similar engine, and I just wanted to confirm the gearing ratio you described (first post on this page) and see if you had any comments about the performance. Your ratio looks to be about 6:1, compared to the 18-22:1 that the kit 2-strokes come with. With 6.5hp though, perhaps it's enough, if you could confirm that would be great!