If you only going to use it once a month to go to a car show or cruise and put 1,000 miles a year on it likely be ok without hardened seats. If just needs the original seats touched up may be ok. Seems the old leaded gas over use would get to the head metal. if cutting fresh material and going to use unleaded gas and will see some miles or other than light duty use best to have hardened exhaust seats installed.
Now the non-smog heads are not fully supported around the exhaust valve and some feel it can result in a loss of press and a dropped seat. In all of them you have to use the right seat as is not much room. Basically you need someone who knows these heads, how to machine them, and what seats use. Finally once you get new valves, guides, seats, valve job, etc... your not far from just getting an aftermarket head. Is a guy down in Florida sells iron heads with CJ valves and hardened exhaust seats. The hardware is ok. Been doing it a long time says never had a dropped seat. Can figure about $800 from him.