Have developed a few oil leaks, was told to go to a vacuum system instead of the valve cover system w/tank. Anyone on this? Also noticed that some systems access both valve covers and others only one side?

How do you use the vehicle? A race engine isn't operated at part throttle much; they need a special evacuation system. Common systems are the exhaust/venturi deals; and belt-driven vacuum pumps.

A street engine is usually run at part throttle; a PCV system in good condition should be enough.

Its a 1966 Chevelle, full tube chassis, 850hp, on Alcohol, track car only, running 1/4 mile