I agree with many of your points Mikael, especially concerning the cooling system. For example, aluminum radiators are NOT an upgrade, only a change. When the stock cooling system is properly bled and working as designed, there are no cooling issues.
Anyway, following are some modifications NOT to do to your Pantera...
1. Cool body mods or customizations
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.