74 Dart - Very stiff ride - Help

Looks like it's launching in the carport :)

Definitely take the weight off the suspension when you mess with the adjusters. The weight of the car will bind the threads and make them lock up.
You might also want to loosen the LCA stud nut as well if you are dropping it that far, then tighten it back up when you have the ride height set and the car back on the ground.