Thanks to everyone who chimed in to this thread. Sorry for the long delay in following up.
I was able to read the radio using DosBox (slowed down to 77 ‘ticks’) on my regular (fast) computer, so I don’t think it’s dead. RSS said the code plug was corrupted, which I expected. I haven’t tried to write to the radio again.
Are the tuning values stored in the code plug? If so, I lucked out as the very first thing I did was download and save the code plug, prior to messing with it.
I’ve been properly chastised at this point and will either send it off to someone to program, if I can find someone, or continue searching for a 386 or 486 that I can run DOS on. Unfortunately, working PCs from that era cost “retro” money. If anyone has a lead on someone with the right gear to program, and the know how and willingness to do the work to program a 146-174 model with ham frequencies (144-148), please drop me a PM (if such things are allowed - if not, I’ll edit this post).