Not my own experience, just what I read here. Some have had fitment issues with early stock exhaust manifolds against late model heads. One member cracked a manifold before noticing the contact. Good luck with your build.
I remember seeing that too. It is on the drivers side manifold only, and is supposedly easy to remedy if it occurs. If I remember right, it is the corner of the head near the rear lower head bolt that is in the way. If it's the bump below the port, you need to be conservative when grinding on the head, because it has been stated here that you can get into the water jacket if you grind too much. A little off the head, and then a little off the manifold would be the way to go about it. I'm in the process of building a 273 with 302 heads....but hoping the Dougs headers don't have the clearance Clarence issues of the manifolds!
