First: It's pretty proven at this point that swinging motors bike are one of the hardest to dirt-ped, simply given the fact that you have bouncing terrain, which causes your motor to dangle, pulsing and slipping the belt. You can get away with a light (compact) moby or pug motor by doing a gas strut, but that heavy scooter case with all that counter weight is gonna cause issues.
Second: what are doing about the clutch? Currently you have no way of clutching the bike, so you either are going to set your belt to be slack at idle, which means you won't move until the cheeks close onto the belt (losing lots of variation) or you're going to attempt to run it with a clutch and suffer from some pretty poor take-off.
Last: Your hanger mount is not going to function as it sits. It definitely needs to be triangulated to stop double-hinged swinging, and to stop it from just rotating itself off.
Paint looks cool, although why you painted prior to getting the engine spring mounts, etc. finalized is a mystery. Have fun, maybe it will work in the end?