Well, again, this is something that should have been addressed immediately with the builder, before trying to suss it out on your own, especially given your lack of mechanical experience and knowledge, but what has been done cannot be undone, so the best we can do is move forward.
So far you have an idea of what the rod bearing clearances are. Nothing jumps out there.
Next up you should check the main bearing clearances, and post the results here.
On reassembly of the oil pickup and pan, I suggest you use thread locker on the oil pickup bolts, and a very thin film of silicone sealer on both sides of the gasket.
It looked like the pan rail was pretty clean, and if you recall I did ask if the builder used any sealer. If no sealer was used on the oil pan gasket, and the correct gasket (I’m talking the master the gasket is made from, the OEM, and the OEM quality aftermarket gaskets) was used, it can be reused multiple times, providing it isn’t damaged.
Once you have the bottom end buttoned up, refill the crankcase and install a new filter.
You obliquely mentioned that you had removed the oil pump, and I’m still not clear if you replaced the pump with new during the rebuild, or if you reused the old one.
Did you disassemble it and check it according to the factory service manual? As I mentioned, the process is detailed in the manual, and is easy to do. You clean and inspect the gerotor (that’s what the two metal pieces are called that actually move the oil), then place the parts inside the housing and use a feeler gauge to check the clearances. If it is determined that 5he pump is serviceable, lubricate it and reassemble.
Also check the pump pressure relief spring. I’ve already shown you where it is.
I suspect there may be a problem either with the oil pump, it may be worn beyond limits, or with the pressure relief spring, it may be broken, or has lost tension, or is simple too weak.
After that, if you still don’t have good oil pressure, you really need to have a conversation with the builder.
And don’t spend a lot of time running the engine until you are certain that it has proper lubrication.