I would also suggest the modern emulated alternatives if you struggle to get hold of the original hardware
MT32-pi: https://github.com/dwhinham/mt32-pi (covers the MT-32 & CM-32, can also do some general midi with sound fonts, so in theory you could emulate a soundcanvas too)
Then there's the sound cards too
PicoGUS: https://github.com/polpo/picogus/ (emulates a Gravis Ultrasound, SB2, AdLib, Tandy & also the MPU401 if you do end up with real midi hardware)
Also gonna just drop the goldlib too: https://pcmidi.eu/goldlib.html but that one might be a bit separate from what OP is currently doing