Double Ditto, on this! Happens a lot when Cheby and Ferd rebuilders do a Mopar! The camshaft thrust plate blocks the holes but not very well, so low oil pressure is often the result. This is definitely not easy to check, so give the heavier oil a shot first. I wouldn't be happy with that oil pressure on a new build either....
I found one plug was missing in the distributor hole and after dropping the transmission and such I finally got it in and back together I'm hoping this does the trick
