That machine looks GREAT although it's a little out of my price range. I just got one in decent condition for $100. One of the guns needs work but I'll worry about that after I pick it up
I have yet to make the drive to pick up the machine, but I played the game when it hit arcades for a SHORT time before disappearing. From what I remember it was fun as hell. Very gory and similar to the House of the Dead games (but much better and gory in my opinion).
The 3 player machine you're seeing is the original Beast Busters. Second Nightmare only comes in one cabinet style (the Japanese version is better looking by far) and both are built as 2 player only. But I do hear it can handle 3 players, so using a supergun and whatever you can find to emulate the guns (which aren't lightguns) would probably work.