Its a Solex 4A1 unless someone has changed it. That was the only carb MB ever put on the M110 engine.
I have seen Holley make-overs and even a few Rochester Quadrajets (almost identical carb except they were always jetted for a V8.) I always wanted to find one (quadrajet) that came on the single overhead cam Pontiacs inline six. It would have about the same displacement and would have done a lot better than the V8 quadrajets.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician