My frame must have been a mouse house.

Id get as much of it out with screwdrivers coat hanger air blower etc.(wear safety goggles) then pressure wash the stuff till the water comes out clean then do it agin a few day's later after some gentle tapping on the frame with a small hammer,it won't take long for it to drain and dry then spray some ospho chemical inside the frame rails any where you can to help protect it from rust,don't do that part on concrete though (it'll stain the concrete)Nice car glad you finally found one you like!!!