If you want to go with new wheels. CCW in florida sells lightweight 3 piece forged aluminum wheels in 17" and 18" in whatever offset you need. Price: $1800.
Here is the website. http://www.ccwheel.com/
If you want to see what they look like on a Pantera I will send you some pics of mine.
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.