not to make it sound worse.. but if you are in there with the head off and do NOT see a visible defect in the gasket you may want to have the head checked for cracks. Most of the time, if you have water leaking into a cylinder it will look markedly different from the others. Another trick, is when you get your engine started crack each injector line and see what cylinders change and what one doesnt. You said your getting oil into the water, are you getting water in the oil? Since the oil is pumping at over 45 psi vs 15ps max for the cooling system, any defect is going to be in favor of oil in water. I would carefully look around any oil passage that is near a cooling passage as well.

While apart, you may want to consider exchanging the timming chain since your halfway there any how. Idk how many miles are on your car, but anything over 150K, keep an eye on it.

Rick