Home made? V12 Scale model engine. 4 stroke, water cooled, 51.5cc

I don’t know much about this engine, it is about 51.5CC, water cooled, 4 stroke and uses glow ignition. I can’t tell if it is home made or if it has come from a factory. It uses a nicely made crankshaft, hardened steel liners, aluminium pistons and some of the components have been anodised. All threads and hardware are imperial size which gives me the impression it was not made in Australia. I built this universal stand for it, fitted new rings (2 rings per cylinder), gave the valves a grind and did a couple of small modifications inside the reduction gearbox up the front to keep the belt tracking on the pulleys better and adjusting some clearances so everything turns freely.