I am trying negotiating the cost, cause 750 is rich for anything. I have been blocked by the sheer lack of candy cabs here in the south (US), I have been looking for a while and this is the first decent one to come up. Every other place has them with outrageous shipping fees, or i would need to roll the dice on a group buy. Truth be told I would love to get my hands on one of those 29" candy cabs.
The street fighter/MK games are not "Must Haves" for me, I would only fire them up for company that wanted to see them. I think I was more concerned about console emulation, those require a crap tonnage of buttons. Again I am not married to the using the cab for consoles either (I have a modded gen 1 x-box I can use for that).
As for leaving it original; yes that would be my plan. I do like the Neo Geo arcade games so leaving the 4 slot MB in there is what I would do, maybe go pick up a neo-geo multi cart.
The other thing I know is that this cab has an MVS harness not a JAMMA harness, and it is my understanding that the only difference is that the MVS is stereo and uses the optional 4th button. So if I use a j-pac (or a jamma board) the sound would not be correct, but the buttons would work properly.
Still thinking I would get the most mileage (compatibility and variety of emulators) out of a custom build, but then again i would need to stick with LCDs and miss out on the "original" arcade feel.