Congratulations on your straight run ratio. That was nice.
There is a ratio of ten hens to each rooster floating around this site as the magic ratio. There is nothing magic about it. That is the ratio that commercial breeders that use the pen style of breeding for hatching eggs use to ensure fertility. It has little to do with over mated hens or roosters fighting. There are reports on this forum of people having serious problems with barebacked hens with one rooster and over 20 hens. Breeders often keep one rooster in a breeding pen with one or two hens and don't have problems. The more roosters you have the more likely you are to have a problem, so it does have something to do with it, but the chickens personality has a lot more to do with it. I think how much space they have also has a very important part in detemining how they get along. Because the more roosters you have, the more likely you are to have problems, I recommend you keep the number of roosters to a minimum and still meet your goals.
You will probably see some problems when they are adolsecents. The young roosters hormones run wild and they just can't seem to control them. They usually outgrow that phase, but it can get pretty rough for a while. And the adolescent pullets often don't cooperate either, so the adolescent roosters often resort to force. That teenage phase can be rough for chickens. Some roosters never outgrow their teenage years. Some hens never learn to cooperate. Some seem to mature pretty young. But it is usualy better if you can weather the storm of their teenage phase.
If you know which two you want to keep, I'd take care of that now instead of waiting. When you remove chickens, you upset the pecking order and they need to sort that back out. With roosters, you also upset the flock dominance situation and that can lead to problems. I think it is better to get that taken care of as soon as possible.
Roosters raised together often sort out flock dominance without you really seeing it happen, just like you don't see a lot of the pecking order getting sorted. Sometimes they fight to the death. Usually it is somewhere in between. Sometimes two roosters will get along great for a year or more, then decide they need to determine the flock dominance again. I can't tell you what will happen with yours. Each chicken has its own personality and each flock has its own dynanmics. With one rooster you are less likely to have problem, but there are no guarantees you will or will not have a problem with either one or two.
I think your plan is reasonable, but I would watch for problems, especially as your flock matures. Good luck!
