Caution on using an 1/2 set collar for the spacer.
Most Mopar distributor shaft are not a 1/2" in diameter where the spacer get locked down. Mopar shafts are generally .4885 in diameter.
Better to bore out a piece of 1 1/4" round aluminum stock or use a 7/16 collar a bore it to size.
Rick Ehrenberg sells the correctly bored spacer as well.
Thanks for the info. I got the size from another car site I am on. I locked tighter the set screw on mine and it has working fine for over 5 years now. But I will keep this info in mind when I add one to my small block 5.9