On these covers, one of them has a bow in the flange surface. The other does not sit flat but the flange surface is more flat. It may be difficult to get these covers to seal. An extra thick cork type gasket may help.
For reference, see our regular Chevy Small Block, Perimeter Mount, Pre-1986, CHEVROLET® Script and Fins Valve Covers, PML Part Number 10430.
These valve covers can be machined for PCV, breather and oil fill holes. There is a machining charge. Holes must be ordered over the phone for specials. See this PDF for details before calling or emailing.
These are sold as-is and cannot be returned. Please call to order.
Top view of both Covers:
Cover that does NOT sit flat:
Cover with bow in flange(can possibly be used with thick gasket):