power steering pump questions

I am cleaning some parts in anticipation of converting my 65 Dart to PS. I have had 2 pumps for a couple of years. They both have the round filler neck (Federal?) but they are not the same internally. One is an early version such as an original 65 and the other is a later version that matches the one in my 1970 Challenger FSM. They both appear to be 1.06 so does it matter if I use the newer style? I couldn't find a reseal kit for the old one but I have one for the 1970 version and I took it apart and it looks fine for resealing. I took the pulley off the older one and it will go right on the newer style so if anyone sees a problem please let me know otherwise I will reseal it and put it aside until I can do the conversion.
Thanks-Howard