I have a SR2 which came with a Brush type alternator. Mine has the housing for a starter motor, but definitely has no ring gear on the flywheel. It did however come with a SOM. Unfortunately, when I bought it and went to fetch it, I knew nothing about Listers, so didn't take the control box, which meant the SOM part was useless. The guy that initially checked it over for me fitted a push button to start it manually using the alternator as the starter motor. I used to manually operate the decompression levers. I never tried cranking it without decompression, so wouldn't know if it will turn over. The starter windings are 24VDC, so 2 x batteries are needed, but the contactor for the push button was 12VDC, so separate wires from one battery had to be used to energize this coil. The electrics in the dogbox on the alternator was a bit dicky, so the charging circuit was putting out something like 56VDC which soon cooked my batteries. There has been plenty of talk on this forum about modernizing the dogbox, but unfortunately my electronic knowledge is far too limited to attempt this mod. I also have been unable to find anyone willing to undertake the job for me, so have let it go and just hand crank. It starts very easily as soon as it gets up to speed. If I remember correctly, the name plate on my alternator clearly states 24VDC. I have attached a picture, but it is not very clear.
