@motorman7
My experience has been that NOS emissions parts for the 73/74Z are among the most difficult to find.
You've probably thought of this, but, the Aussie's had the 260z for several more years (till 78??) than us in the U.S. and many of the parts are the same.
I was thrilled to find a NOS EGR assembly from there for my 73 Zilver. Actually, as I got further into the restoration, parts came from all around the world (Kuwait, Turkey, Greece)
{ @Patcon }
You "might could did up" a contact to @Gav240z and enlist his help in finding a few of the items you need.