Hello mowermechanic

Well, this mower is significant in that it was Victa's first rear-catcher
lawnmower (along with the 4-stroke Ambassador.)

These are easy to date: the 1962-63 Lawnmowing season, that is from
September 1, 1962, to August 31, 1963. It was one of four new models
for Victa's 1963 line-up.

Yes, the engine is definitely wrong. A quick give-away is the
carby on your machine is on the wrong side.

I am currently writing a History Record on the Viceroy, as luck
should have it. That will be available shortly.

In the meantime, I have made available (for download) an excellent
Victa Mower Manual. It should answer most of your questions:-

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=70029

Hope this helps.
---------------------------
Jack

p.s. best way to remove nut (without damage): impact wrench.
[Your local garage could do this]