The first thing to check on Mustangs is the torque boxes on the sub frame under the area of the driver's feet, if they are rusted out there will be serious rust problems elswhere.
When you go to look at a car like you are looking for always go prepared to crawl around under the car, and search for rusted areas.
Thanks for the advice.
I’m in western Washington where it isn’t so much wet as it is damp. It doesn’t take much trapped moisture to start a good crop of mildew going but other than slight surface rust where the paint was scratched or rubbed through (like the window ledge where you rest your arm) the damage to the interior was limited to the upholstery. Rubber parts like door seals were manageable.
When I tried the door the latch mechanism worked and the door opened about an inch before catching. I knew that if I forced it something would give - and it might not be the hinge.
I’ve always wanted to restore a ‘67-’68 Mustang so I will keep your advice in mind as I inspect them.
Thanks again!