I'm the owner of the only known board for this. Purchased it last year. It WILL be dumped at some point, but until then I can't say anything. For those wondering, it is just a normal Final Fight PCB with changed eeproms, nothing special otherwise. There is another bootleg/hack out there called Final Crash, but it's not the same.
Once I get an eeprom burner and I feel comfortable it will be dumped for everyone to play.
I just played it the other day to make sure it was still fine and it played the same as the first day I got it, so no worries, it is still alive.
As far as it being on any of those multi-boards, definitely not. I haven't seen anyone else that has this rom set anywhere. I'm literally the ONLY person on the planet that has the board/roms as far as I'm aware, though I'm sure it's probably still running in some 3rd world arcade venue somewhere.
I posted in the thread below shortly after I received it, denoting some of the unique things about the hack, and other differences. I have since found out that some of those are likely due to the DIP switches, which I won't be touching until after I have dumped the roms:
http://assemblergames.com/forums/showthread.php?t=16756 - My post is #13 on that thread, same ID as here.