I would drive out the roll pin & add some flat (non beveled) shims to reduce the axial play to .005" & you may need to in addition add the collar but first lightly twist the rotor back & forth with the dist still installed, not enough to get into the springs & see how much rotational play you have right now (you want very near none). speedway motors has a kit for $10. this may not be the issue for this situation but it is good to address it (it mainly causes spark scatter when timing it on the dampener) & a sloppy timing chain will do the same thing & a sloppy chain will skew cam degreeing readings.