JMHO, but a couple of things come to mind.
Timing;
10* initial doesn't sound like enough for a cam that has 12" vacuum at 970 rpm. I would try 14-16* initial with 36 max. And check your vacuum advance, I would suggest you plug the vacuum off until all tuning is done, then use ported vacuum for it. And check the mechanical advance curve, you may need to adjust it. And as Mike P says above make sure your timing is steady with no worn parts.
Carbueration;
Have you read the plugs for proper jetting? This could be incorrect jetting, and check the metering circuit, the rod springs tension may need to be adjusted.