1997 Dodge Caravan oil in radiator

I had a timing belt 3.0 engine that went bad it got hot only a little, while I was in the front I sleeved the crank seal and replaced the water pump, after start up, miles 400 or so milky antifreeze or oil in the water, no heating problem no water in the oil, is it possible that the new water pump is letting engine oil in the system without putting anything into the oil?
or do I have a head gasket or crack happening? I flushed the system but that oil milk is bad stuff to completly get out to put in bars leak best engine stop leak to no avaiil possiblly since it was still residue stuck with the oil antifreeze goop. Ideas?