Better late than never, I always say!

Done. I took the suggestion to core out the old t'stat and use it and an old chunk of hose to direct the block overflow away from the front of the engine and into the recovery bucket. Gotta' be green. When one can...

I flushed with nasty old hose water for 7-8 minutes and then switched over to 5 gallons of distilled (7-8 minutes) until gone. I'm cheap!
It's city water-not well water. Neutral pH. And that's what the issue is.