Parts stores make no distinction between the two types as far as bearings and seals. That indicates to me that the spindles should be the same, however, it is never a bad idea to measure and be sure. I would think the rotors would fit the drum spindles directly (if using early rotors, at least).
Clarifying for myself: You are wanting to put early rotors on an early drum spindle? Or disc spindles in place of the drum spindles? I would think the disc spindles would be a direct swap, as I can't see the logic in Ford using different ball joints/tie rod ends, etc. If it were me (since you're going to have to make mounting brackets anyway) I would almost just start with the stock drum spindles and go from there (but it is early, and I need more coffee lol).