-SG- Rod in Australia has had some new drive side mainshafts made for his mid twenties 16H: he has four spare which he is willing to sell if anyone is interested. In my experience (let me stress I have only changed a very few in the last fifty years) this component remained the same on all SV and OHV engines (exc. CS1/ES2/350s) from around 1924 to 1929 but don't take my word for it. Check with Rod re dimensions.
He has also had some primary chain guards made for the same period - again there are four surplus to needs which are available. Contact us for Rod's email address.