Bitter taste of defeat! So much coolant in the oil pan.

To add to the above: The water in the rad test may indicate the pump area if you have a thermostat in the system. Pouring water in the top of the rad will back into the upper hose and direct into the intake if you have no t'stat. So use that to help judge which way the water was going. The timing cover with the pan on can be hard but can certainly be done successfully, and maybe you missed locking into one of the pins, and cracked the cover..... just a SWAG. (Looks like MM thought the same.)

I'd start with the water pump, then timing cover. Keep an eye out for any obvious clear water trail when you open it up there.

Once you find it, wipe down every area and part you can reach as you button it back up, and run a couple of cycles of cheap oil in the engine for a few minutes at a time and drain it and change filters each time to cycle the water out; you have coolant everywhere inside now. And then run it for maybe 15 minutes and change it again , and keep at the frequency oil changes. Make sure your PCV is working as its' gonna be doing a lot in the near future, and change it out once the issue has subsided. Then keep an eye on the new cam and everything for a while.