If you are willing to spend, and when I mean spend I do mean it, Roland actually released a VST that emulates the Sound Canvas near perfectly. The Sound Canvas VA is what it is called, emulates the SC-55 up to the SC-8820, and it works perfectly for old school DOS and Windows games that use General MIDI.
Check out the video from Phil's Computer Lab about it, really is a good piece of software: https://www.youtube.com/watch?v=WumRboSfn90
$125 is a bit steep for a software synthesizer... A few months ago I managed to acquire a real Sound Canvas SC-55 for $40, which has the MT-32 mappings (no SysEx programming though). Wired to my mixer with built-in effects processor i miss nothing of the SC-88 functionality, and can set the perfect balance between MIDI and digital samples volumes.. Still even the "real thing" is often inferior to a good soundfonts, so I use it only for games that are specifically SC-55 programmed and balanced. Warcraft 2 is the perfect example of a game composed specifically for SC-55 and music sounding crappy or at least not so good on any other MIDI device (big sound-fonts included)
Of course it is steep, which is why I said if you are willing to spend. :P