Toyota Repair: Water in my oil due to overheating, cylinder head gasket, toyota timing chain

Question
I have a 92 Toyota pickup 22RE; The engine over heated and got warm a number of times, at least 3 in a 2 month period of time. I changed the radiator and everything seemed to be fine, for about 2 weeks.  Then one night while I was driving the engine started running rough and it died. Until that point the engine was cool and running fine. Needless to say I checked the oil and it looked like chocolate milk, I assumed that I had blown my head gasket. Now I am in the process of rebuilding the top-end of the engine. My question is when this engine over heats and the oil/water mixture happens where other than the head gasket can these happen? I'm planning on checking around the water pump and the checking the valve seats. Looking at the cylinder head gasket I cannot see anything that looks too bad. Are there other places, seals, which can cause the oil and water to mix if they are broken/ruptured due to overheating? Is it likely that the block could be cracked in some spot that I am not seeing? I'm kicking myself for not at least compression testing the cylinders before taking the engine apart, where should I go next? I still have to take off the Timing chain cover and chain but after that I'm stumped. I'm almost ready to take everything in to a service garage. The # 2 and 3 cylinders are clean and the 1 and 4 are normal looking so what ever happened happened in that area.

Answer
More likely the timing chain was worn and hitting the front cover. If the chain is loose long enough it rubs a hole in an area where the coolant passes and then the coolant will leak into the oil.
Since the head is off continue the repair but do the timing chain and guide. Don't use non Toyota timing chain parts, they don't last as long.
Good luck
jack