Oil pressure concern

I just had a local Mopar engine builder do a 360 to 408 stroker for my Duster.
Using all good parts from Mancini racing. The motor seems strong, I have not drivin to too hard yet, it has about 200 miles on it. My concern is low oil pressure on idle, when its in gear, at about 6 to 800 RPM's, the pressure is between 10 to 15 lbs. Above that it holds around 50lbs when driving. It has a mopar hv pump with a windage tray and stock pan. I'm using a autometer mechanical gauge with copper tubing, there is a tee on the block so my factory guage still works, it stays just about in the middle all the time. The 340 that was in the car before seems to have a little more pressure on the factory gauge, I added the autometer for a more accurate reading. We plan on droping the pan next week to replace the gasket, it drips in the rear of the pan only after I drive it. I wipe the pan dry, no more drips. Would that have anything to do with oil pressure?
Any input on this?

Thanks