I did a clean install of 7.5.3 again, then upgraded to 7.5.5. It now recognizes the adapter, but it didn't install Open Transport nor AppleTalk v.60 this time. I've kinda left off on trying to go further, I'll see if I can get online once I get a CD drive for it so I can load iCab or something of that sort (perhaps Internet Exploder).

I have 7.5 on Apple floppies, but 7.5.3 and 7.5.5 were downloaded from Apple's old software page, then passed over piece by piece by floppy. Not fun, 22 parts to move over that way.