Blue is older than the red labelled tags and much more common to use throughout the late 1960's. I'm not positive but I think the red stuff started appearing very early 70's although others can confirm.
If you're looking for a complete Day 2 ignition, I have a fully restored YC-310 Rev Pol Distributor that was just rebuilt by Jim Lander and tested complete with matching Rev Pol Coil. It is setup with NOS Mallory Wires, has a spare set of vintage White Pro Stock wires, spare rotor and a Rev Limiter Kit with matching blue control dial for under dash. PM me if you need more info on it.
