Well, I went out to trouble shoot the cooling problem today.  The thermostat relief passage was properly sealed by my welder.  Just to shed some more light on the subject I decided to start the engine with the outlet hose disconnected.  I ran the engine for 2 min. and not a drop of coolant came out the opening!!!  No coolant flow whatsoever, nada, zip (the system was verifiably full of coolant, the pump drive was turning.  So its either a broken shaft (but the pulley turns smoothly) or something really strange (like the wrong impeller).  Unfortunately, since I have less than ¼ inch clearance to the firewall I really don’t think there will be any way to get the impeller off without removing the engine.  Ahg.