If you need to enlarge the coolant pipe holes, McMaster-Carr has the appropriate stud driven hole punches. They have the grommets too.
Further to Julian's comment, I spoke with an engineer at Stewart Components years ago, who felt that an electric booster pump, placed as close to the output of the rad as possible, would be a huge improvement.
Stewart also has some awesome 351W belt driven water pumps.
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.