Toyota Repair: oil pressure, oil, pressure

Question
just rebuilt a 1983 22R toyota engine, replaced crankshaft, timing chain,new valves, oil pump,water pump. truck will start but has no oil pressure.

Answer
Did you put the pick up tube back on?  It is in the front part of the engine in the oil pan.
Did you put the oil pump gear back in? It is driven by the crankshaft.
Were all the gaskets replaced or were some reused?  A reused gasket could be leaking internally.
Is there no oil pressure AT the oil pressure sensor or on the dash (The lead on my 1985 Celica GTS 22REC came loose once.  Showed no oil pressure on the dash, but I had pressure at the sensor)

Hope this helps.

Vince