Central Texas , Bastrop county | Ive had the same experince with an exhaust manifold on a 350 small block Chevy engine. The engine had overheated to the point that it quit running. I installed a replacement engine from a junk yard and when installing the exhaust manifolds, one of them was a little less than a half af a hole off. Fortunatley for me, I was able to elongate some of the holes enough to get the bolts all in and it seems to work with no leaks. At the time, I did not think about why that happened, but now that someone else has experienced the same thing, it now makes at least some sense.
Jack |