Classic/Antique Car Repair: Exhaust Manifolds, gmc sprint, waist time

Question
If I get the original exhaust manifolds ported and ceramic coated (On the inside) , will they flow anywhere near a set of Headers?  Thanks   Matt
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-----Question-----
I have a 1976 GMC sprint with a 350 engine. The Cylinder head on the passenger side appears to be smaller than the one on the Driver side. I can see about a 1/4 inch in the top of the block on the passenger side, and the drivers side Head is flush with the engine block. I am not really sure how that is possible. The engine has been this way as long as I have had it. About three years. There are no visible leaks , it just looks weird. Is the head suppose to be a little shorter on one side ?   Thanks   Matt
-----Answer-----
MATT;
I would not even worry about it, it must just be the casting markings, they did not clean that side off as good.  ok

Answer
Matt;
 NOTHING will replace the headers, and I think you would waist time and money doing that to the manifold. unless you are going to try and cheat at the race track, and headers  are run as stock at some tracks. as the headers have a tube for each cyld. and they are bent for the best performance,  I would go for a set of headers , nothing beats a set of headers and you will feel the diff. you can even go for a cheeper set if you do not have the funds.  ok