it's not really an "issue". basically, brooks saddles don't have as much setback as the more mordern designs.

1. buy the brooks and mount it on your existing post.
2. see if you can get it where you want it, fore/aft.
3. if not, buy a post with more setback.

personally, i'm running a B17 on three different bikes and a B67 on two others. i haven't had to resort to a different post on any of them.