I would be very surprised if there is any refrigerant left in the systema after that time.
The A/C system typicaly leaks down without use to maintain seals, most pantera's require an annual top up to compensate for winter losses whiel aprked.
If it has the original York piston compressor, then you are better off pulling the system apart and upgrading to a rotary compressor IMO.
Julian
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.