Using a quart of oil every 300 miles. No obvious leak, compression test perfect.
So no leaks and compression is fine? But how is your exhaust? Is it blue and do you leave clouds of smoke down the road? Your valves seals might be leaking. Burning a quart every 500-700 miles in my book would be engine rebuild time.
go here if there is smoke coming out or a weird smell when your near the exhaust http://deadlimit.blogspot.com/2012/05/smoke-problems-and-solution.html
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