Most older arcade monitors would use RGBS, same as you are, but through whatever plug they liked wired up to the Jamma socket - i.e. it didn't matter what plug. Sometimes the plugs are common molex, most of the time you'll have to wire something.
However, most old arcade monitors will want a video amp to use with a PC. The Jpac from Ultimarc works well, and takes a VGA cable straight from your PC. It outputs to a Jamma edge, which plugs into the socket in a lot of older cabs. If you don't have a cab, just the monitor, you can buy a jamma extender, cut the wires where needed and then bridge the RGBS to the arcade chassis through some screw terminals or something.
Personally, I'd pay money for a nice presentation monitor that will also do 31/45kHz, as getting a decent larger Nanao monitor, the Rolls Royce of Arcade monitors, isn't going to be cheap.