If you had a way to safely compress the suspension you could measure some. Stock the springs are something like 500 # per inch of travel. You will never be able to compress the full amount of travel available to the suspension without the spring and shock.
Even if you could do that, you could not compress it the entire route. Only a few inches.
I don't know anyone who wants to do it that way. It is simply too dangerous.
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.