Ok coach if it is running now put the light on it with the dist unplugged.. Set it at 6/8* btdc and run her around a bit. If she does NOT clatter you can advance it to 9/10* and run her around some more.. That is about all the advance I would put in one. If she runs and idles good leave it there.
Your slight idle miss might be a small vac leak somewhere and it might be AGE/WEAR.. Many of these never get the smooth constant idle that you might want. A different carb might not help any at all.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />