If financial resources are not an issue, consider the 5.0 liter 4 cam. The 4 cam engines are heavier than you might think, the aluminum blocks maybe the best choice if not supercharging.
Mark, great pics, now I know why I didn't see your car at Tech Day.
http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=6787
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.