Finally got around to measuring the distance between the center of the my drive sprocket and rear axle. It is 25.75 inches. That is with an 18 tooth drive and 42 tooth driven.
Sent my info into Scootworks to see what's available.
I'm pretty sure that the Bonneville rear pulley they have should fit our America & Speedys. Front sprocket on the 270 engines should be in the same location as the 360 ones (same engine). That means that the placement of the rear should be the same between the two bikes.
Does the Bonnie rear hub have the same bolt pattern for the drive sprocket as an America?