Hello Sir Bat, Patrick, Kye and all,

The numbers are no surprise then.
They fit in nicely with my reasoning. Close Kye - 10/01/1961.
And yes, it did have a wind-up starter.

Spare Parts Manual here:-
https://www.m-and-d.com/pdfs/briggs/80900-ms4216-0188.pdf

You can now sleep in peace Sir Bat.
Perhaps new info will come to light at a later date.

p.s. Would you have a full view photo of the machine from the front?
[including the handle]

Thanks for the update.
--------------------------------
Jack