No kidding that crossed my mind when first looking at it. WTF?

 

Cripes! OK, that changes everything. It doesn't appear to be a bolt!
Your best bet, as mentioned, is to bring it to the builder. Even if they
missed it, they still have an obligation as an engine builder to know
better and to rectify the issue.

 

Probably an old injury that scabbed over.

 

It is best to have the shop put it up on a Boring Mill or a Vertical Mill of sorts and bore it out with an endmill. Then they can progressivly open it up with a larger drill or endmill.

A compentant machine shop can remove that with no problem. Run a tap back in there afterwards and it will be good as new.

 

well called the shop today, and will be bringing it up there tomorrow.