The largest contributing factor to the value of the cars over time is a very active, visual club like SAAC.
It is harder to do with basically only a couple of models but things like this forum help.
If you think about the Vegas run then you know that there is solid support for at least the Pantera and the Mangusta.
Publicity at a national level helps a lot. Car values are like currency values in that they are only backed by consumer confidence.
The greater of the illusion that there is something there the better.
There really isn't anything on the right coast to come close to Vegas. The Pocono event doesn't get much press.
The solution is just a lot of little things over time and there is no way to add race history to the marque.
Detomaso should have been nicer to Henry way back. After all if you look at it, it has been Fords money all along that sponsered the successes in the Ford family.