I'm running a real mongrel cooling system on my 47. I've got a stock radiator with a zero pressure cap and a coolant recovery system, no thermostat, a stock NAPA waterpump with no bypass (either internal or external), run 100% propylene glycol coolant from Evans Cooling, and dual electric pusher fans with no engine fan. Even with a zero pressure cap the Evans NPG+ coolant has a boiling point of 275 degrees, so I don't worry about it boiling over and losing some. It starts warming up on the stock temp gauge about 5 blocks from my house, and usually runs between 160-180 degrees. The fans kick in at about 190 degrees, and usually only come on in heavy stop-and-go driving. I've only seen over 200 degrees once; a few weeks ago when I was driving on the freeway and a waterpump bolt backed all of the way out (!!) and dumped most of my expen$ive coolant all over my engine compartment and fenders!
The only problem that I have is that this stuff tries to leak out of every place possible, as it is pretty thin. I've sealed every bolt going into the block and the head, and had to resort to heavy duty T-bolt hose clamps torqued to 100 in-lbs to stop the leaks at the radiator hoses.
As they say, to each his own!
Marty