Gaylen,
Bob, the resident Villiers nutter, is away on vacation at present, not due back for a fortnight, but I am sure he will give you a more than comprehensive answer when he returns.
Villiers were proprietary engine makers, so they sold engines to anyone who wanted to build their own machines.
Miller were proprietary manufacturers of lighting sets for bicycles and motorcyles, and supplied to lots of different manufacturers.
Gear shift through the tank sound like a very distinctive feature, and I have no doubt that Bob would make an ID from that alone, however, I have no idea. Dates it to early thirties, I would think. If you can list engine and frame numbers, that would allow a complete identification. A photo would be good, too.
JFerg