Also, if your timing continues to bounce around with a non-digital timing light.(I bought an MSD made light), a collar on the distributor shaft may stabilize it. Hughes sells them as do many hardware parts houses. It's just a 1/2" locking collar.
My MSD was also very far out of phase. I had to use the MSD adjustable rotor to get it back to where it should be. It was so far off that the added energy it took to make the circuit from the rotor to the distributor terminals melted the tip of the rotor and it fell off.
I've since pulled the MSD Pro-billet and replaced it with a bluetooth tuneable distributor from Progressive Ignition. I really like it, and I got my vacuum advance back.
