Reminds me of one of my first "hacks" (not a fan of the term). When I was younger while looking through the racks of a computer hardware shop I noticed that the 14400 baud modem they had on display had more than a passing resemblance to my 9600 baud modem. I pulled my card and brought it back to the shop and examined them both closely until I found that the only real difference appeared to be in the memory, and the uart ic. Feeling a bit adventurous I found the exact same 16550 uart in their catalog, and a similar memory chip, ordered both and soldered the memory and replaced the socketed uart.
Fired it up, expecting to see smoke, or at the very least have it not function correctly, but it worked very nearly 100%. I could connect to local bulletin boards at 12,600 (I believe, my memory might be off) and occasionally at the full rate. Most things worked well except for downloading. I couldn't download using x-modem or g-modem and had to use streaming protocols like y-modem and Kermit.