There has been a considerable amount of good help in this thread and there have been a lot of assumptions. The first major assumption is the motor was built properly with the correct parts. From what has gone on, my first guess would be the balancer and timing cover are mismatched, but it needs to be verified.
The balancer is apparently coming off anyway, so once again remove the timing cover. If you can see piston #1 through the spark plug opening great; if not get a bolt in piston stop and confirm TDC. Check the timing gears to make sure they align.
Put the cover back on and slip the balancer on and check to see if the balancer and 0 on the cover line up. If they do, it is one issue that can be eliminated. If not mark the cover where it lines up to 0 and make a new pointer. You can buy a pretty chrome one at a parts house or even drill a hole and use a nail tack welded in as a pointer.
Once you know the mechanical timing is right, you can then recheck the valve clearances, take the distributor to an old time shop that has a distributor machine to make sure it is all good, set the timing, make sure you have good fuel and see what happens. It is difficult debugging over the web , but with the good ideas and differing thoughts going back to the basics may make sense.
Best of luck!!!
