Because vendor inventories vary it is impossible to know who has what product in stock. The valve cover you are looking for is temporarily out of production until the pattern can be repaired. As far as the side cover is concerned, Offenhauser never made that item....
Assuming you still have the original engine (1970 and later heads are different) you will need Offenhauser part number 5205. 5205 is an adapter. As you stated, the intake is integral to the cylinder head. Using the 5205 kit and having machine work done to your...
Although Offenhauser never made a 2×2 intake for the Buick Nailhead engine, part number 3413 (3×2 manifold for 1953-1956 Buick Nailhead) was designed to be used as a 2×2 manifold by blocking off the center carburetor with part number 1097 (3 bolt...
If all three of your carburetors are 3-1/4″ X 1-7/8″ (which is the small base) you will need part number 4060 drilled for the small base Rochester carburetors. As for the other manifolds you reference, 5257 is for three (3) Rochester large base carburetors...
