When you have it idling at 1200 rpm do you know what the timing is at 800 rpm? It may be into the advance mechanism at the 1200 level and when you drop it in gear that advance is gone. Might need someone to help you with putting it in gear, foot on brake and seeing what the results of that test are. Or, just turn the idle down and watch the timing mark, doesn't matter if it's right or not, you want to observe if any change occurs.

If you are questioning whether the balancer has turned, set, initial using the vacuum gauge or strater kickback method. Set total by the 'where it doesn't ping' method if you don't remark the balancer using a TDC stop. Note where each of those numbers fall and use them as references in the future.