I did the conversion on a friend's '67 Coronet using one of the kits of new parts but some parts had to be modified. This was a kit based on the '73-6 A-body. The holes in the spindles didn't line up with the lower ball joints.

On my '64 Dodge, I did the conversion with factory parts off a Dodge Dart and it worked much better, no problems with bolt holes being off. And much cheaper.