Good job yes the 1964 223 is going to be the easiest one to do the 240 / 300 distribitor swap except for changing the drive gear it's a drop in. All the other years of 223's can also use the big six distributors you just need to eigther change to the 1964 oil pump or make an adapter from the current oil pump drive to the distributors 5/16 hex drive.
I may of gave you some bad info on the HEI shaft oiling problems this is a problem on the units made for the small block Ford six'es (170, 200, & 250's not getting oil to the lower shaft bushing and they would Seaze up, sorry about that. At this time I don't know of any problems yet on the 240 / 300 made units and of course your HEI when used in a 223, but the stock big six Ford Distribitors seem to work fine in a 223 so chances are if there is enough oiling at the drive gear and bottom of the shaft then the HEI could work fine also. As far as the top oiler this dose help keep the upper shaft bushing lubed and extending its life span a good idea however on the newer models this was discontinued.
I think I rember talking about that 223 NAPA rotor being too loose a while back, the problem isn't in having the wrong rotor its because there is a spring type clip that is missing that is suppose to slip on the end of the Distributor shaft. Without that clip then the rotors made for those distributors doesn't fit on the shaft properly or be as snug as its suppose to, these clips are also still available new or maybe it was still stuck in the old rotor when you took it off? Best of luck