I considered using a CRT monitor and ArcadeVGA, but the cab was already going to be big and heavy. With the advent of HLSL incorporated into MAME I decided to use an LCD monitor and emulate the CRT instead. I'm using a beefy PC to run it all; i7, 500GB SSD, 5TB external HD with all the games, GTX 970.
For the marquee I used an ultrawide 25" from LG, the main screen is a 720p 28" tv.
I removed the old mount for the light in the marquee area, and installed one that would accommodate the monitor. I could mount the old ballast in there again if I want to revert. I also installed a new arcade power supply as the old one was dead. The power strip to run the monitors and the PC are plugged into the 110 AC service outlet on the arcade PS, which is operated by the original switch at the top of the cab. This means I didn't have to touch any of the wiring, and have one switch turn on for the machine (though software settings in the bios).
I added a set of 4 switches just inside the coin door to operate the software volume (mute, vol up, vol down) and service to get into test mode for a given game. I'm running an AHK script to make it work.