'68 318 - Coolant left in heads when removed.

I removed the heads from my 1968 318 Barracuda to take them to the shop and when I removed the heads a LOT of coolant spilled out, even though I let the radiator drain down completely. I can also see sitting coolant in the passages in the block. Is this normal? What is causing this?

This made a mess that I immediately cleaned up. I also am unsure if any coolant could have gotten in the oil. I believe the oil ports are all above the cylinders where oil would ramp down the head to the block over the cam. Should I also change the oil?
Happens. Change the oil, no big. Costs maybe 30 bucks. The coolant in and out are up at the water pump ...so anything below 'aside from what's in the radiator' isnt going escape ..till you pull it, put it on the stand and tip it over into a catch pan.