You should use OS 014BOE on any G20-G23, standard or MLD screen. There is also a "show" version of that OS though...
If you happen to load that "show" OS, you cannot cashout, and it has menu items in the system itself to add credits, display a bonus screen, and other things that would be on a "demo" machine. That's not what you want.
So if that happens, look for another 014BOE OS that's a slightly different file size, which should be the normal 014BOE OS loader that you should use.
Works the best on all systems. Good to always have by itself on a small FAT32 formatted flash drive so you don't have to hunt for it if you ever need to do a full reload of a machine.