Pontiac Repair: Low oil pressure, crank shaft, low oil pressure

Question
Hi Just having a 455 Pontiac engine done from scratch for my 1977 Trans-Am.Machined block to very high standard approaching
8.0 LTR with bores. new crank shaft, cam, pistons, the whole works.
The mechanics have told me the usual oil pressure reading is around 80 + but at present its showing between 15 and 30 the oil pump has been tested and replaced but oil is getting to the front lifters and the bottom end is well lubricated but the rockers and remaining lifters are still bone dry. Thought possibly blockage but everything is brand new ? any advice ideas much appreciated thanks

Answer
Hi lewis:
when is is supposed to have 80 PSi ater what RPM? there is no way it will have that at idle hot. A good rule of thumb for a non "built up" stock engine is 10 PSi for every 1,000 Rpms. so if your reading is 15 psi at idle hot I would say that is pretty good. do you have valve train noise with this lifters ticking etc??? With out knowing what this engine has in it for parts including the oil pump I have NO clue what it should be Sorry I can't help you out too much..