Check to make sure your PCV is working correctly. If your intake below the carbs is shiny with oil, that'd be the place to start.

My only other thoughts would be to ask what style valve seals do you have? The umbrella style or the positive seal type?

Reason I ask is that I have a similar problem with my AMC V8. After a hard romp, most of the oil is pumped into the heads (AMC's are notorious for poor drainback issues). My top end is old and worn and with half-assed umbrella style valve seals and a rocker area full of oil, lots of oil gets past the seals and into the combustion chamber.

My symptoms were also similar. Good Compression, acceptable leakdown, functional PCV and dry upper intake.