Also, you wouldn't "have" to pull the distributor and reposition the rotor. Simply loosen the clamp at the bottom of the distributor and turn it to match the mark you made and see if it runs there. I can't think of a reason at all the plate inside the distributor would be off in any way to have to modify the cap.
The clamp bolt is right at the block level on the vacuum advance. Slotted screw driver will loosen it. Then turn the distributor a little to line it up with the mark. Try not to push down or pull up on the distributor while you turn it.
