Low or no oil pressure on new engine, wtf now...

My dad installed the cam, I wasn't present so i don't know how it rotated, he's no amateur at engine builds, so I know he would have checked the bearings and the new cam. Didn't inspect the pump, that's what we are leaning to, the relief spring. Have not manually pressurized it yet, we wrapped this up at about 7:00 pm last night, so today is theory and cover our bases day.

I will say I have no knocking noises, no smoke, both exhaust pipe are clean, clear and even. But we are not running the engine until the pressure issue is worked out.