Now that I think about it, you are probably referring to Laslo Antal's wheels, which are a larger diameter but still retain the deep dish look of the 15" originals. However, those are custom original one-offs that I understand were fiendishly expensive. I imagine custom body work would be required before you could get them to fit your car, but if money is no object you could always contact Laslo and see if it would be possible to have another set made up.
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.