I would go with the CJ heater box, heater core and chevy blazer blower motor upgrade. It rocks. Also, it wouldn't hurt since you're draining the radiator anyway to put in a new thermostat as well.
However, it will depend like Mike said on what dash (controls) you have.
All the Jeeps I've owned
79 CJ5 258 six with a weber (current vehicle) T18/Dana20
81 CJ5 258 six (driven out of Alaska thru Canada in winter with a softtop)
75 Jeep Wagoneer 360V8
79 Jeep Cherokee 258 six