How are there some Victor airways that exceed the service area of the VORs they are identified by?
It says it right there on the page where the service volumes are described in the AIM:


  1-1-8. Navigational Aid (NAVAID) Service Volumes
  
  c. Standard Service Volume limitations do not apply to published IFR
  routes or procedures.


So V267 has been flown at the MEA by an FAA plane, and it obviously met the signal accuracy requirements to be usable at the distances charted.