Sorry to be a critic, because I agree with your concept, but the photo of the rolling chassis emphasizes the disparity of the wheel sizes.
Not a good look. Using spoked wheels would solve this problem, but tube tires would reappear.
Cast wheels of the proper size means probably using a chain drive.
Good luck! Suzuki should have done this!
Cheers!

ps: a 120/90 on the rear might lessen the rear 'heavy' look and not affect the rideability.