Could berelief valve or poor oil return something some of the big chief style stuff is known for. Also having the vacuum pump hooked up is not going to help that. Not unusual for us to have to add extra oil on the dyno. Be curious to see what he finds, the SB in the Vette we have to run a couple extra quarts in it, just does not seem to like running on the dyno in a static position, in the car we go back to 6qts with no issues, I know crazy.
We took the belt off the vacuum pump and that helped with the oil pressure. We were able to make a full pull on the dyno but when we finished the pull the oil pressure dropped way down at idle so we shut it off. This is the second time on the dyno. The first time the valve covers filled with oil and we couldn't make a pull. He added drain back hoses and had a new pan built. Those changes fixed some issues but it still isn't quite right. We had 8 qts in a 7 qt pan which might have been too much. We didn't want to run it low since we knew the valve covers would hold oil. I suppose we could've tried higher and lower oil levels to see if there was a solution.