There were a BUNCH of AH General Magazine articles for War at Sea, including:
Vol 13/#3 which added variant counters for the Med,
Vol 14/#3 which added the French navy,
Vol 15/#3 which added the Russian navy,
And according to my AH General Index of articles, there were several other articles that added optional rules, and these included other counters as well. The article names do not invoke what sort of counters, but the entry then states V + C which means variant rules + counters.
Volumes that include that sort of entry include:
Vol 14/#4 Victory at Sea
Vol 15/#6 Realistic Victory at Sea
Finally, there is an issue with an article titled The SHips of War at Sea (Vol 16/#3. Wonder if that is a rundown of all the various ships, or just a brief history article.
I have most of these issues (everything from Vol 14/3 until they closed up shop with Vol 32/3). I could pull them if that would help. But if all you wanted was the formula, I think you have that already.
Pity I only just now realized that there were variant counters to WAS in Vol 11/3. I probably would have made an effort to track down Vol 13 back in the day to get them. WAS was/remains a very fun game.
Steve