At the risk of sounding like a smart a$$, I have to say that most old cars leaked when they were new and 60 or 70 years hasn't helped them. In the case of early post war Fords like mine and yours, they were really poorly fitted at the factory. Most of the trunk lids I have looked at don't exactly fit the body opening. Some are just better than others.

My car has leaked around the windshield ever since I have been driving it and I did use correct gaskets. Part of the problem is the inset glass and modern speeds. The water piles up around the recessed windshield and high speed wind pushes it into whatever small opening it can find.