I have a set of 14x6 ralleys from my 68 ... The car was drum ... Not sure if they fit discs or not . We could try them on my sons 68, he has factory discs on it. The wheels are in good shape with center caps and trim rings
To determine if disc or drum wheel look at the back inside , if the rolled edge from bead goes straight in it will fit disc brakes . If the rolled edge goes in then has a step in it [ creates a smaller i.d. ] than drum wheel only .
Jody, Seems like you probably only really need 2 rims for the front to clear for disc. The 2 for the back won't have to clear a caliper. Easier than find 4 that match. Just a thought.