It does look rather like a cut off two piece flo-jet, as you say. He may have cut it off at the choke, because the part to the right of the choke is just a mounting for the air cleaner. Remember there are several kinds of flo-jets: that one is a large 2 piece. The large one-piece is rather more common. It looks like this:

[Linked Image]

The one-piece is easier to fit to vertical-crankshaft engines because it bends to the right, which gets it out of the way of the exhaust port. The 2-piece bends downward, which is fine for horizonal crankshaft engines but on verticals it requires an exhaust pipe design that gets out of its way. That is why I think you need to get proper original parts for both intake pipe/carburetor and exhaust pipe. If you use the wrong carburetor you have to expect problems getting the governor linkage to work.

That engine is unusual, in my experience anyway, because of the centrifugal ignition advance system. I think it would be a sufficiently rare bird in Australia to be worth preserving as an interesting model.