3 SD from the mean would be 99.7% actually.
So that means basically you think 3 out of every 1,000 guys is worthy.
Seems a little overly exclusive! :)
2 SDs is 95.5% which would be like 4–5 guys of every 100. That is definitely more reasonable but you also have to define WHAT you will be measuring. Lots of different stats and metrics this could be for.