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It is a pretty easy fix if you have a machine shop handy. They will put it on what looks like a really big belt sander and true up the sealing surfaces. Even if you were going to replace them I would true up any set of manifolds just because of how cheap it is to do and it makes for so much better sealing.
Handcannon's advice is correct....UNLESS you live in a hot State (Texas) and don't want your exhaust manifold superheating the intake. I always separate the intake from the exhaust manifold and mill off almost 1/2" from the bottom of the aluminum intake. I then make a blockoff plate out of 1/4" steel and bolt it and a gasket onto the exhaust manifold to seal off the gasses from the intake. I also remove the exhaust flapper valve and weld up the pivot holes. If you do that, your fuel is much cooler as it enters the cylinders, and your intake and exhaust mounting bolts/nuts just need to have a large washer under them to even the load across both manifolds. On my own engines I either weld some aluminum to the intake, or braze the exhaust to get both manifolds at the same height, so I can still use the original round washers when mounting to the head. You definitely still need to have a nice flat surface on both if you want a tight seal to the head.