What should an engine sound like?

I would have a look just to be sure the rocker shafts are oriented so the top oil flows on both sides, no scaring underside of the rocker covers, etc...
I just stated in another thread how engine building compares to child birth.
Being a tentative parent means paying attention and that's a good thing but...
some will wear out their hood hinges with worry. We'll watch a new baby sleep too so... It is what it is. Good luck with it