Hello Bullucked
A warm welcome to these forums from me.

Yes, most definitely a Qualcast Royal Blade De-luxe.
It appears the original tank failed ...
This one has a Victa Rotomo tank modification.

The engine is a JAP Model 80 design.
Magneto should be a Wico 1-1259

A record is available here:-
https://www.outdoorking-forum.com.au/forum/u.../qualcast-14-inch-royal-blade-c1958.html

I'm not sure what 2-cyle engine theory you have to identify the issues here.
I'm hoping a member can help out.

Please keep us informed as to progress.
These would have been a most handsome machine when new.

Hope this helps.
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Jack