I just had it running on my GDEMU on my CRT with 2 lightguns.
Works great bar a few minor issues...
It was a little hard to get into the menu, took a few attempts but got there in the end. Niot sure if that was down to my old guns or the game.
I found the reload kept trying to reload between shots so it was screwing up my gameplay.
I found changing it to handgun or auto in the menu fixed that issue.
The only thing I could not get to work way Player 2!
In the test menu it would not register my second gun plugged into port 4, I tried swapping the guns to rule out a gun problem but that was ok and I know the port is good as I tested it.
So other than P2 not being recognised working good on gdemu