As far as custom dies go they probably won't be a advantage unless you have a custom barrel and gun. LarryIf your chamber happens to be standard in all respects you are likely to get standard dimensioned dies and the custom die maker can stick the extra cash in his pocket. You have not specificed anything custom and the custom die maker has not agreed to any specific changes.
If you want custom measure your chamber and specify what you want in your dies. Otherwise custom might get you nothing in particular.
If you want custom benefits you really probably need a custom chamber.
This custom chamber makes the rifle shoot much more accurately. The custom dies work with the custom chamber if they are really needed.
I have several custom chambers in a few benchrest rifles and I do not use custom dies made for my chambers. My dies are simply Wilson neck size bushing dies and Wilson type seaters. I do have several sets of "custom dies" but they are no different in function than the Wilson dies. Two of my chambers are tight neck requiring no neck sizing so the only die needed is a seater.