Thanks Bruce, The only Information I have is that it is A Pope walk behind Mower Vertical Shaft Engine (2 Stoke /Single Cylinder) Rotary Valve Possibly 150cc. The bore is 2.375in (60mm) Carby is an Australian made Zenith Model Number: AH914

Not sure of Model or year I Googled AI & it said that it is from the 60's era after giving it the only numbers I found on the Flywheel cover

Engine Model: 7503 -02
Serial Number: 53606

I can't post photo's of the engine because I don't know how!!! ( Not that smart) My computer skills are limited.