I bet you dont have one of these.
I am no expert but I can remember when the first rider mowers started selling and they never had an engine like that with a mower. Riding mower engines are still pretty much similar to when the first ones came with the rear engine and would stand on its rear wheels every time you released the clutch and usually ran about 10-12 HP. That 10 HP back then would still pull a 38" cutter which was about as large as they made IIRC.Wow only 1 1/2"HP ???
They do not show a model number or the year but this surely is nothing original, except maybe that engine.
The wheels, seat and shell look like a newer mower to me.
I am not an expert by any means, but I do wonder what the real vintage design looked like with a mowing deck.