The Victa full crank motor as you have there is, in my view, one of the best engines made for rotary push mowers. If properly maintained and run with the right fuel mix they can last 50 years or more between rebuilds. Even then, in most cases, only new rings and bearings are required.

G2 carbys are more prone to issues than the later G3 and G4/LM. Many G2s were replaced in period with the much more serviceable G3, they bolt straight on. You can pick a G3 up relatively cheaply, or even free if you drive around during hard rubbish collection. The G3 isn’t a totally bombproof solution and some folks do have issues but I have three mowers I use regularly that are close enough to 50 years old fitted with them.

If you can’t easily get a G3 then a G4\LM as suggested by Norm will be your next best bet. There’s a bit more mucking about to fit the G4 though so that’s not going to be everyone’s cup of tea.