The folk at RRD make some good stuff, though I'm not familiar with this particular system and I really need to stop buying new ones.
I think I'd probably look more towards Free Kriegspiel Roleplaying principles rather than anything especially solid. The games you described functioned more like a Braunstein than anything else and what you need (and as I recall, was something those forum often games lacked) are high trust independent referees with an interest in making the game good, rather than simply fun for their friends.
It would be interesting to see if that kind of thing could work under an OSR/NSR style of play though, the ones I have had experience of were much more s-game or neotrad orientated. You also might want to look at the west marches campaign model if you haven't come across it.