I would go with opinions above on valves or rings but there could be many more. Like blown head gasket, cracked cylinder head or cracked valve seat. One of the hydraulic lifters could have lost it's seal or almost gone. Does it have a lot of clacking noise from that side? If the pressure test is done with the air put water in the cooling system then have your friend check the radiator at the same time for bubbles. Also on the fuel pump is the rod actually not moving or could it have to big a spacer between the block and pump? It doesn't take much to reduce the action on that lever.
Anyway just a few other things to think about. Those 396(402)'s are pretty nice engine's to have and getting scarce.
