Yes, the distributor drive can be moved. While it is possible that the timing chain jumped a tooth, I don't think this is what you are looking at here; your timing chain would have to be pretty sloppy for this to happen.
Just so you know (if you didnt), you have a distributor drive under the distributor that connects to the cam via a helical gear. The bottom part of this drive is a shaft that runs down to the oil pump so that as the cam turns, it turns the oil pump below and the distributor above. The gear can be adjusted or moved because as you may know, the bottom of the distributor has a flat tip that goes into the slot into the gear. The gear is moved so that when the distributor in in place and point at #1, the vacuum advance isn't point at/hitting the firewall or intake.
If your timing chain jumped a tooth, you would have metal in the oil and usually they don't just jump one tooth, usually when one goes more follow as the chain becomes even looser.
In my experience there can be a fine line in timing settings especially in a performance engine. So based on what you are saying, when you have the timing mark lined up with zero on the timing tab the rotor in the distributor is not pointing directly at #1? Or are you are saying that it is not pointed at #1 but is between #1 and #8 when the distributor is at 12* advance?