water in the oil

There's also a water pump bolt that if too long a bolt is used it will bottom out against the outside of a cylinder and if is's continued to be torqued down on will result in cracking said cylinder. That would be a bad day.

That said, what "I" would do is drive it. Put a few miles on it and see what happens. It "could be" left over coolant that got into the oil pan when the heads were removed, OR condensation that's set up in it. In either case, it will boil out of the oil and evaporate.

If it does not after a couple of moderately long drives, well then, you have a problem.

What head gaskets did you use? What were they made of? Were they stamped steel? If so and you did not coat them, they are likely leaking. More information here might help.