Oh, and to answer the actual question, any Delphi can be updated to present specs (Mk. V) - the newer it is, the less expensive the updates. But the most expensive update is the Mk. V motor/plinth combo @ ~$1.5K. That one is really only necessary if the motor has a problem, the rest are more likely to improve sonics on a better value for dollar basis...
The VPI's are a bit tougher, as not all parts are available from VPI anymore on the HW-19 series, however all Scouts can be upgraded to higher models.