wouldn't an army outfit more likely be a M20 BSA ? 600cc sidevalve single, all torque. . or a WLA harley outfit, these were common once 750 flathead (sidevalve) V twin. reverse gear too.

Yes agreed, they already have a BSA, ...the brief is

....Anything that could be mocked up as war issue as long as it has a sidecar.There is a pic of a local who was a despatch rider at the museum during WW2 on a Norton hence the preference

The intent is to use it in  parades, field days and displays under club rego. The Jeeps, Landies and Blitz are used at Local Anzac parades to carry those veterans that would find it hard to march the distance.