I bench-tested the PC hardware by plugging it all together on, well, a bench ... and installed the OS, then when that was happy I transferred the PC guts into the cabinet and connected the KeyWiz to the motherboard.
You can safely do that much without installing emulators/front end until you're out of the "playable but unfinished danger zone", assuming your bartop's design still gives you access to USB somewhere for keyboard/mouse/external HDD etc, which I hope it does!