Small (pinball) world. I'm doing the same on my 80b. I suggest using an Arduino over the Pi. The Pi is great but it is WAY more computing power than you need for a simple receiving-and-translating of the 5 sound lines. With the serial communication you can easily control the Sparkfun/Robertsonics WavTrigger. When my sketch (Arduino code/program) is completed, I'd be more than happy to share it with you.
As for mapping the sounds, there are a couple options. First, using the route I plan on going (Arduino+WT), program the WT to have 31 tracks/sounds that simply say "one, "two", etc. Then go through and manually trigger the sounds one at a time and keep track of what sounds are played. In this method, it will help great deal if you know the order of sounds generated when starting a game (coin up, start, launch, everything up until switches are being hit mid-game).
From talking to another PSmember whose name I forget but they started a thread about custom 80b sounds with a RaspPi, the "one, two three" sound track method has its cons. So another method which is the route I am going is this: http://www.beerorkid.com/pin/Gottlieb%20Sys80/s80sound.htm
May have some useful info regarding your previous problem, though the info mostly pertains to 80/A, a lot of it is transferable to 80b. Scroll down to find the TEST JIG
Of course, this requires having a working soundboard. IIRC from your previous thread, your board doesn't boot up correctly but once the machine is on, the soundboard works correctly if you manually hit the reset button. If so, this could work for you.
As far as finding someone who already has the sounds mapped.. doubtful.. I mean, you are talking about a Raven
Another option, when I am done with my project, Ill sell you my 80b soundboard. Or I'm sure you could procure one on your own. They do pop up on eBay now and then.