If it was on only for a few seconds, then this is normal. Sounds to me that you received a defective engine.... The fact that it started and ran fine and then fizzled after 5 minutes or so would indicate this - especially with a complete long block.....
This kinda reminds me of my atx oil pump that I replaced. When I rebuilt the tranny I bought a NEW atx oil pump instead of rebuilding the old...since they fail. The new oil pump has a whine to it. It has become more quiet over time but there is still that whine. Most noticeable when in gear and stopped. You can hear it from the outside but not from inside the car. I have been told that this has been a common problem with the new specs on these new pumps. Nothing fails but it is a little loud........and I do kinda notice every little thing on the car if you know what I mean.
Bob
