Well, here is the problem(s) with a 54 FORD (as it was a changeover year).
The car (as it was built) can take four different front hub-drum assy's and there are two drum sizes for the rear. They are also different from 55/56. It depends on the brake size(s).
The actual brake size(s) will be given in the 1954 FORD WSM at the end of the BRAKES SECTION (SPECS).
Do you have a receipt for the K-H drum? Maybe call the seller and ask what their listings say.