Ditto what Jeff just said, We tossed those out years ago as they were simply the worst sounding synths ever. They were among those first generation " digital" multi timbrals. They sold to fools like me that used it for live gigs running from an Atari sequencer. Rolands MT series were the same junk.
I would say the MS wavetable synth will be far better.
Just because it's old means nothing, It is not the same as finding an old analog synth which do have uses. In post 8 you have the correct hook up.
I think it was only a 3 channel synth and you'll have to send the correct channel to trigger it. It will need some internal configuration.