I don't think its one of those either. The buttons are weird.
Hence my pointing out that the footrest and marquee bend being different from most System 2 cabs, but there are several variations of
System 2 cabs.
Can you get a better shot of the serial number plates on the back, especially the black+white one on the upper left?
An Atari System 2 cab probably would have the Atari logo like the serial number plate on Joel's
Paperboy.

Check on the inside, especially on the back door, for other identifying marks as well.
This cab has probably been converted several times.
The 3-in-one buttons are often used so operators don't have to drill more button holes in the CP when converting to a game that needs more buttons than the CP has holes.
Scott