I chased an oil leak on my SBF, and even went to the trouble of pulling the pan and replacing the gasket, thinking it was leaking around the rear main. I finally realized that my oil was coming from 1) the breather caps (no PCV), and 2) the fact that the valve cover only met the mating surface of the aluminum heads about 1/16", and the thick rubber gasket was rolling with torque (a stock FelPro gasket overlapped the top edge of the heads, but the bottom edge of the covers). I replaced the cast covers with a pair of fabricated covers made by the head supplier, and made sure that they had baffles at the ports on both sides. I replaced one breather with a fill plug, and the other with a direct mount PCV. Oil leak solved. The lack of baffle plates was a big part of the problem, but the mismatch in mating surfaces was the killer.