Intake Manifold leaks Coolant- Could it be too small??

I bought a used Weiand 7510 aluminum intake for my LA and cannot get it to seal. The rear coolant ports both leak. When I removed the intake, the metal gasket ridges were not flattened, and it does not appear to fit. As a sanity check I compared the fit on the head with a cast iron 2bbl manifold I had and noticed that the Weiand has side to side play of 1/8" to 3/16" without gaskets, while the cast iron has zero play and is flush. Before I spend bucks on a new manifold, I thought I'd ask FABO for comments. Anyone know of a way to tell if the Weiand has been resurfaced? It seems fairly straight front to back on each rail, but it is definitely a bit narrower side-to-side than the cast iron manifold. Will thicker gaskets work? Or should I bite the bullet and buy new? As always I appreciate your comments!
Did you take the locating dowels out of the china walls? What engine are you working with?