While I think, do you know if the moped specific tyre is needed for Low Power, and indeed, is it actually required for 28mph bike?
I've worked out that a small carb minimoto engine and the 4:1 reduction box will let me gear down 5:1 on a chain to the back wheel, so that's not a big problem, just the nit picking over what brakes, lights, tyres I'm alowed to use.