[Kisner]

One other thing you might want to check is to make sure when you're adjusting the heater that the cables are actually moving the flaps to the correct positions to allow the warm air in. When I restored my 68, I took everything apart (heater box and all the other parts), cleaned them real good, re-painted them, installed all new gaskets, and threw the old heater core away. A new heater core only cost me I believe around $25 or $30. I also make sure that the various flaps and vents were opening and closing properly when I put it back together. I also replaced the switch on the front of the heater box (can't remember exactly what it's called) that the blower motor plugs into. If your hoses are routed properly to the heater core, there's no blockage anywhere, the heater box and plenum vents are opening correctly, and your thermostat is working properly, you should be getting warm air. My 2 cents.