I’ve always been intrigued by the Italjet Amarcord concept bike from 2001. It used a standard 125/150cc GY6 scooter drivetrain, but mounted it amidships, rather than out back with the wheel attached directly to it, scooter-style. A drive belt transmitted power from an extended transmission output shaft to the rear wheel — an arrangement similar to a lot of Chinese youth 4-wheel ATVs.
The engine bay of my Aermacchi 350-SS chassis is long enough, I bet I could fit a GY6 engine and CVT in there.
I’m not saying I will, mind you. I am just thinking out loud. Though, “Aermacchi Amarcord” does have a ring to it.