CB36
You will enjoy the 70 in the cub. I flew a .70 in a GP 40 size cub once (76inch span) and all I need to do was keep the throttle down. It flies quieter that way too!. The 11 ounce tank will be fine just because you will not be on the throttle hardly at all. I really don't know what to say about the real need to lower the tank. I did with my Cub and with a 90 Surpass in a UCANDO.46. Since it is a 4 cycle it might not be as critical as a two cycle, just don't flood the carb and try to force start it with an electric starter. Keep the carb closed while filling and don't open it until you are ready to fire. I installed my filler fuel dot on the top of the fuse in front of the windshield. I won't be ready to fly mine for another couple of weeks as work travel is getting in the way. Don't know about the balance. You want it a little nose heavy.