The oil pressure does normally drop as the oil warms up and this is stated in the manual. These motors are not known for knocking when they are healthy and their bearings work very well. They just use an outdated oiling system.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!