Just out of curiosity: What do you hear when you select Sound Blaster as music device (instead of General Midi) e.g. in Doom?
With the Sound Blaster option selected for music in Doom, I get something similar to OPL3, but slightly more tinny sounding (MP3 is attached). For comparison, I've also attached an MP3 of Doom in General Midi with the Arachno sound font loaded. Also, here's a picture of the card in case the model number matters.
As for the SB16 emulation, here's how I went about it. I first downloaded this Audigy 2 ZS CD image and then the 9x DOS mode support package, both from the Vogons driver library. After burning the image to a CD I installed the drivers. For reference, I chose custom install and deselected everything except Windows Driver, SondFont Bank Manager, SoundFont Banks and EAX Console. After the installation finished, I ran the Creative Driver Utility Program and selected "Install VxD Driver". When that was done, I made the registry change mentioned here, installed the 9x DOS support package and added the SB16 device a second time, as instructed in that thread.
After all that, I just run the Creative SoundFont Bank Manager and load the .sf2 file that I want. Any games running in the Win98 DOS prompt use that sound font when I choose General Midi.