Hey barnes. Ive been thinking about this as well. I just bought 2 of these for the same thing.I think I'm gonna go with a 13" or 15" tube and try to keep the width of the control panel to around 15" wide. I really want to make a mini dedicated MK bartop cab that is still playable.
About the wiring, i just took it apart and it will be simple to do. The main game board has a strip of wires coming off of each end. 1 for the punches, kicks, and block, and the other for the movements. These strips are soldered to the button boards. the buttons are all labeled and its obvious what wires go to what button. And the ground is clearly visible also. Instead of soldering on the button spots you could just cut the whole button boards off and connect the wires to a terminal no soldering necessary. I hope all this makes since. Its as easy as cutting wires then extending them to your actual arcade buttons. I'm gonna use the 24mm pushbuttons from GGG since I'm trying to make a small CP, still looking for some small joysticks.
I don't know if you've actually played the game yet but ill write a mini review of the game. I would put this port in between the snes and the sega in terms of graphics and sound. It has all the correct fighter motions(unlike sega) and all the blood(unlike snes). The scrolling backgrounds don't scroll,the court yard folks are still, i don't think i saw any background animations. there is a split second of loading during the endurance bouts in between fighters but not enough to bother. No options which doesn't bother me (for cab use i prefer no options). Different title screen it looks like the marquee from the arcade. The sound is a lot better than the sega version but still not up to arcade quality but it is in mono. I would rate it higher than snes and the sega for the best home port and my reason is , the gameplay feels like the arcade (which to me is the most important), the game is better than the sega version in every way possable, the game doesn't look as good as snes but i think the inclusion of blood and the original fatalities trumps the graphics issue. I totally think its worthy of being built in a cheap bartop cab. Sorry for the late response but Ive been trying to find these things for cheap before i purchased them. I hope this helps.