Yes sir. I'm mathy as well and I undersized mine the first time around, and trust me, that looks small. For a 6.5 hp you're going to want to overload it on the lower end to the point that the clutch slips, otherwise at the top end you'll only get like 10 mph which is nothing. I had all of these trials and tribulations during my first iterations, so from a learning standpoint giver er a go like that and let us know how it works!