"I have them on my dart but it's mini tubbed and leafs are moved in board"
I have the same set up on a 65 dart which is narrower by 1.5" I run a 4.5 BS on the wheels with room to spare. Be aware of the quarters and understand the upward travel.
40 years, in all seriousness they are pretty similar from what I have seen. You may want to check out ET wheels they are repoping the 5 spoke and you can get a 15" in almost any pattern. http://www.team3wheels.com/et/index.html