Amiga uses a totally different sound system. IIRC Amiga used samples instead of synth. Adlib, used FM Synth (forgot what FM stand for off hand,) but I always thought of it as a much improved SID style music (showing my C64 roots here, I know.) Basically it's given a set of values for pitch, frequency, attack, decay, etc... and the Adlib card converts that into sound.
GM/GS is pretty much a standard for MIDI (GM = General MIDI.) GS is supposedly GM+, I've not done a lot of research into the difference. But in a game's settings you might find an entry for "General MIDI", "GM/GS", or some variation of that. These work differently than Adlib, in that different values are supplied, and like the Amiga, a sample is used instead of wave form calculations. For GM/GS, the note and instrument are what is provided (Trumpet C# for example - though it would include octave as well,) and the device (physical or virtual,) plays the corresponding sample with the frequency/pitch adjusted to match the note/octave.
MT-32 is basically pre-GM. GM has become the standard, but from what I understand MT-32 is more versatile. But it pretty much works very similar to GM/GS.
I don't believe that Adlib values can be easily converted for GM on the fly. It seems that it would take a tremendous amount of calculating to do so anyways. The only way I can think of doing it would be to take the values given, build a virtual waveform with it, adjust the pitch/frequency to the standard (reverse calculating note/octave,) then compare it to all the "instruments" in a standard GM set to find the closest match. The program could then send the calculated instrument with the reverse calculated note/octave to the GM device. There may be easier ways of doing it, but that's all that I can think of.
All of the games you've mentioned (not counting Eye of the Beholder 1 & 2,) are Adlib or MT-32 (Monkey Island 2 also lists SoundBlaster - but that is probably it's Adlib mode.) The games you mentioned will not, it seems, play through GM when set to MT-32 modes. I would suggest checking out Munt (here on the Vogons board,) a MT-32 emulator (though you'll have to track down the ROMs for it.) It will add another MIDI device but all the games will sound MUCH better 😀
So, for the games you've listed so far, I would say: Cruise for a Corpse, Monkey Island 1, & Monkey Island 2 will all sound best with MT-32, but without that you're stuck with Adlib music (one of the games offered Game Blaster, which is probably CMS - or pre Adlib compatibility sound blaster.) The rest of the games you listed, I'm afraid your stuck with Adlib as the best available. For all the games, I would run their setup routines and set them the way you need/want. On a side note, my disk versions of Monkey Island 1 & 2 didn't have setup programs, I had to manually tell it to use Roland (or Adlib, or whatever,) at run time. I don't know about your versions.
To test the BASSMIDI, you'll need to find a game that can be set to GM, will play MT-32 through a GM emulation, or find a .mid file to play through media player.
p.s. As a note, the only legal way to get the ROMs for Munt is to purchase an MT-32 or CM-32L and dump the ROMs. Though, I guess you could contact Roland and ask about getting the ROMs.