Who knows. I thought I remember it being thinner than standard 25" cabs. I could be thinking about my Sega Turbo, which is pretty thin. I was like 24yrs old... and now Im 39. Thats a long way back to remember.
Just measured the Turbo. 9/16ths.. which is a mere two 16ths over 1/2". Sorry, but my Terminator Scanning eye is off calibration a bit

heh
Anyways... here's a rough mock up of how a cabinet could be made to break down fairly easily.
Its not to scale... nor complete. Just a concept.
The simplest method, is using simple small strips of angle iron on the corners of the bottom half. Though, that is also the heavier solution. Figure (C)
A simple 1 x .5 strip set could be used Figure (A)
Or a 1 x 1 block set with a wood or metal dowel set, as in Figure B1 & B2. Fairly Precise drilling would be needed... though, you could at very least, drill first, then cut the block into two parts, for each top and bottom cab sections. Make sure to mark each piece however.
The Corner mounts keep the cab in place, where as the Arcade control panel Spring-Clamps, can be used to pressure them tightly together. It probably would only need two of them... however, adding either 2 per side... or a total of 3... (left, right and front) should be more than adequate to keep it rock solid.
Control panel not really considered much here. It could use similar methods, a slide lock+clamp, or simply bolt in place. Not all CPs even have to come off.
* Remember that you only need something like a 3" strip per corner. Not an entire internal framework.
* Also, make the entire Cabinet first... then cut the Cab in half. That will keep dimensions precise... rather than trying to build two accurate parts that fit perfectly together. Use a Fine tooth blade on a circular saw if possible... and or route away & sand any rough edges as needed. Take into consideration a few MM of lost height from the cuts.
* The door(s) could be a single traditional lock & pop-out. Or could be 2 dual hinged doors. Or could be a single 'removable-pins', hinged door. Solid doors can add a lot of mass... so removable... or at least thinner wood, is a big plus.
Edit: On second thought... Pop-Hinges would probably be a bad idea. As they are external, and you still may wish to slide the cab on its backside when going up/down stairs.