Hi Everyone! I haven't posted in a while.
[Edit: added this line.] To answer the first question, rebuilt. To address the second...
There are many factors that add or subtract to flathead cooling, certainly the water pumps are an important component, I think we can agree to this.
The folks at
www.fordcollector.com are water pump (and coil, and other pieces) rebuild experts (as well as experts on varied vital subjects), but who use "improved" replacement parts in the pumps related to the impeller, at least I think. (See the referenced thread above.) Their pumps are on many members' engine(s), I have a set waiting to go on mine when needed. [Edited: Added here.] The member above, Cecil, from personal knowledge he's an expert mechanic and driver, and friend, BTW.
(On the coil subject I was treated exceptionally fairly by this supplier when they fixed one that was destroyed through no fault of their own. So even if their products are not the replacement for sliced bread, the business is headed in an admirable direction as evidenced by their reputation, some would say innovation, and product support.)
The thermostat question still hangs out there. I run with none. I'm not saying I'm smart, but it works for the miles and terrain I drive.
The pumps in question come with recommendations, including using coolant additives and using thermostats from a recommended supplier. Not especially good or bad, just good to know in advance.
My $0.02. If I was tearing an engine down, I'd pay particular attention to getting the block clean. Many stories about dirty blocks are floating on the forums. Then I'd contact Mr. Haney for advice on pumps and your coil(s) including your backup. [Edit: Added here.] Then, being on the East Coast, I'd send the whole lot to Walt in Maine, then I'd pay the bill, install it, and I'd drive it for twenty years!
I hope this helps.
-VT/JeffH