http://mirror2.ipdb.org/files/966/Williams_1990_Funhouse_Prototype_Manual_Addendum.pdf
This indicates the sound board, sound roms and transformers are not compatible.
WPC-89 sound is run off of 18 volts.
I can't tell from the IPDB schematic, but sys11 sound boards operate off of +12, +5 and -12. If the 18 volt transformer is used on a 12 volt sound board, damage usually occurs. If the 12 volt xformer is used to operate the 18 volt sound board, it probably won't work.