Oil consumption issue
 

I'm hoping someone has some insight about possible causes for a peculiar oil consumption problem that I'm having with my '72 350. I rebuilt the engine .030 over, new pistons, rings, valves, guides, seals, seats, oil pump, cam and bearings, high vol. pump, etc. Quality parts, all as close to stock specs as possible. Heads and block were professionally done at a very reputable machine shop. After 10k miles, it was continually getting worse, using about a qt every 300 miles. All plugs were loaded up with carbon, all pistons are caked up as well. Hardly any smoke visible when running. No Leaks. Engine actually ran very smoothly. With the pcv valve out of the valve cover, it still used oil.
The engine is now apart. Oil rings have full contact in correct arrangement, with good drag in the bore. Compression and vacuum were good.
What am I missing? Any ideas?

You say the oil rings are properly seated, but it sure does not sound/act like that is so? Are the ring gaps properly alternated:

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