Being a "1973" and its EDPM, its time for a new roof replacement anyway. If wondering, EDPM sheets and underlay glue can be purchase as "special order" from many RV dealers. Lots of great DIY You-Tube videos showing the install as well. If replacing roof surface, remember to fully inspect its underside wood sheets as well. If needed, do upgrade thin 1/2" plywood sheeting with much better tongue / groove 5/8" sheets. Its much stronger in the long run.
If not into DIY mini-projects like this, then ask a few technical schools in your area if their students are looking for special projects. A few technical students would love a DIY project like this. I'm sure they could re-cover aluminum roofs as well (assume you supply the needed materials).