Bushie, looks good so far mate. The LM and G4 carby parts are not interchangeable so dont mix them up.
The carb you use is up to you but the gauze on the jet is critical as it acts as a filter to stop debris from blocking the jet. The idle knob was made obsolete by Victa as the average consumer was dialling the idle way too low and was causing issues like fouled plugs and blocked mufflers as the oil was not burning out of the fuel mixture.
As for the muffler i'll have a look if i've got one and let you know.