Hardened Valve Seats or Not?

Remember that you only have so many valve grinds on the valves before the seat area is too thin.
Did they replace the valves when the heads were done years ago ? If not you may already need some new valves when you repair the seats in the heads.
It is always more expensive to do a job twice than to do it right the first time.
Whenever you are short of money, re-adjust your priorities and wait 'til you can do it correctly.