Hi DSS,
I don't know whether Epic Endeavours was ever played in multiplayer. Multiplayer may require specific handling in the mod (for instance to avoid other players to wander when an important dialog is running) that I'm not sure the mod complies with. Besides, I don't even know in details what is required.
It may be a good idea to run the first test (introduction of the game), then the first mission (for instance) in multiplayer. If you're able to play without problem, chances are rather high you won't face an issue in the mod due to multiplayer (some other bugs may remain, I'm afraid).
The mod doesn't have any dependency on a specific existing
NPC, so you may make a full 6 player team without incompatibility. Unfortunately, the 8 players capability is, as far as I know, just a dream. The 6 players limit is hardcoded in the game engine.