David, in addition to the O.D. ratio, also consider the transmission's first gear. My TKO 500's first gear is a 3.27, which would be fine for drag racing but since I don't bother doing that with my tiny engine, I do wish I had a lower number first gear ratio. First gear is SHORT! All that being said, I do like my .68 fifth gear even though I don't have a lot of high gear torque. I like to do road trips that have me cruising 75-85 MPH and in my high gear, the engine is just loafing along and I have enough torque to make a gentle pass. If I need to be spirited, fourth and sometimes even third gear come in to play. Love to hear my sewing machine engine sing.
My 2¢
BTW, I run a 3.50 rear end ratio and 26" tires.