The lack of gaskets on the valve chambers is not causing the cylinder leak down. Two different animals. Your cylinder is worn and needs replacing. that is the reason for the leak down. You most likely have the original 3-Ring Type piston. As Dan said, if it ain't broke...Next time have the manual handy fo R&R and a parts list.
FORD 9N/2N ESSENTIAL MANUALS:
Tim *PloughNman* Daley(MI)