I acquired a 57- or later 261 with an 848 head on it. It appears that someone at one time hand drilled holes in the head to match the 261 steam holes on the block. A couple holes if not all appear to have been poorly aligned to the block and the holes were made wider than what they should be. Should I be concerned about this? I don't have a picture to share becuase I just buttoned up the head to the block. Would this affect the water jacket on the head and how the steam or coolant will flow? I installed a new head gasket and used copper spray as well. Tommygun

The coolant holes in the head may be drilled at a 12-degre angle, as discussed in this thread. This could cause them to appear slightly wider or non-circular.

I may be wrong, but as long as the holes in the head are not so poorly made that they do not line-up with the holes in the gasket, and that they don't leak, you should be ok. When I was young and ignorant back in 1958 when I built-up my first 261 back in 1958, I was not even aware of the steam holes and I just bolted my 848 head on without drilling the holes. As long as I was running a fan there was not an over-heating proble, and the block did not appear to have suffered any damage.