Hello Jack,
Very elegant! I love the on/ off switch below the dash….where did you get it? I’ve not thought of a rheostat, seems obvious now you mention it. I’d thought of a downstream thermostat before the rad, because (in the 7c) we’d get cold and the water never got above 40 deg. I put a 4mm hole in the thermostat because I didn’t want the radiator to freeze. The current one has an adjustable blind between the rad and grille, as well, so we’ve thought of everything….except salt…on the roads….oh dear!