Well, some major changes to report. Although I haven't done much lately, I have learned that Polypropylene will be a superior choice to Ryton. Therefore, I will be acquiring a Polypropylene Volute for the existing pump, and the second pump (should it be needed) will have the Polypropylene housing. Big Flub-up on my part. It'll be fine for testing, but once that's complete, the volute will be replaced.

The engineer I spoke to with the manufacturer advised that Ryton becomes brittle at low temperatures. I could use it, but I would have to be absolutely sure that the plumbing doesn't apply stress to the volute.

I was able to find a TE-5-MD Pump motor on Ebay with the motor drive magnet. All I need is the pump head. The MD-SC variety is about $140 bucks. So if the second pump is needed, I've got a source for an identical pump.