OK, the MT-32 works fine on my Win 7 PC connected to the MIDI ports on the Audigy 4 Pro breakout box and used via DosBox. So no problem there.
On my retro PC I have finally managed to install the Sound Blaster AWE32 DOS drivers and get them working as the installer would only work on DOS 6.22 / Win 3.1. So I installed the drivers manually.
I've got one of those Gameport to Midi adapters but the MIDI cables are not marked IN or OUT. They are just the same both black.
Also, what exactly would i need to set to use the MT-32? AWE32 option in games in DOS (proper DOS not command prompt) works perfectly.