8" at 200 yards is good for a military BPCR. In fact, I would say you could certainly participate in a match and get a respectable score. The problem would most likely be that most matches only permit black powder, and for military rifles you are usually not permitted to clean between shots. That means you have to get experimenting to find how much of what lubricant your rifle needs to get through a match without cleaning! Why not give it a try?

Patrick