Al, the rubber seal can be replaced. There's a dimple in the stick.... flatten that enough to allow the metal cap to slide over it, replace the rubber with some tubing the correct size, then slide the metal cap back and use a punch to restore the dimple.
Prices for the 2x4 manifolds keep going up. $400-$550 is common. Carb pricing depends on condition, could be a few hundred each if they're decent. Linkage is reproduced, and the fuel lines were also but don't know if they are still available.
