Just had a little test drive around the block (just to heat up the engine) and all went well. Thermostat opens up and temperature keeps its 'normal' level. Couldn't get it to heat up so far as to start the fans, but I didn't want to rush things. At least its not leaking!
I saw a couple of coolant drops under the engine, but those drops may well be a remaining of the mayhem of dissection. Tomorrow i'm going for a real drive to check it out.