97 DOHC oil dumping into coolant.

I am working on a friends 1997 dodge neon 2.0 DOHC.
The differential pin broke in the tranny and destroyed the tranny case, so we decided to rebuild the engine while we have the engine/trans out. Well got the rebuild done, had a slight knock. I thought it was just noisy lash adjuster. Well about 2 week later it started knocking bad and loss of oil pressure. So I tore it down and found a spun bearing on #3 cylinder. Replaces the crank w/ a remanafactured crank, connecting rods (eagle h-beams), and piston and rings again, all bearings again. Everything was done to spec.!
Got everything back together, except for radiator and coolant, started engine and had still had a knock bud after a few seconds the noise subsided some, no oil light, let it run for a minute or so, then oil light came on and a few seconds later oil starts pouring out of the back of the water pump (where lower rad hose connects to) I'm at a loss, the only thing I can think of is a cracked block. Any suggestions, ideas, common issued?????

Thanks Joe.