I wanted to take a moment to throw a shout out to forum member "Clemsonteg". He sent me a very good heater-box (for nothing but the cost of shipping!) to replace the rusty one that was in my truck. We've got some good people here I tell ya! Here it is with a new heater core and a gasket kit from Classic Parts.
Unrelated, but I picked up the flywheel from the machine shop today. All pretty and smooth.