i think you will be doing more motoring then you plan.. i was a avid mountain biker before i motorized my bike.. i would ride miles a day. but once i put the motor one its all i wont to do.. it really is a blast.
plus to pedal my bike with the motor is a workout.. after a mile or two its almost to much. and im running a lighter 2 stroke.
i guess if you have gears on your bike it will make it easier.. good luck with your build. i hope it all goes well. and put up lots of pics. we love pics!