Ron,
The good spacers are machined concentric, Five percise stud holes and one large hole for the hub. Stay away from the mega-fit anything cheapos.
The 67, 68 4 piston calipers have a couple of little tits (cast ports) that can be ground for clearance if you don't want to use spacers, I could not ruin original patrs even if I needed to.
Jon,
How did you run those for years without damaging both the wheels and the calipers?
VT