should i have hardended exhaust seats installed

I've heard both arguments and agree with both sides to a point. That said, I think if I were rebuilding an engine, I would do it. Mainly because of the ethanol added in today's gas. Why? Ethanol acts as a drying agent. Without lead in fuel, seats and valves are already running hotter than their leaded counterparts did years ago. Couple that extra heat with the extra dryness of ethanol and IMHO that makes things even hotter. What actually happens to the exhaust seats is, they get so hot that they weld small particles of themselves to the valves and then those particles are blown out the exhaust. That's called valve seat recession. Used to be, before unleaded fuel, a dirty air filter was the main cause. Minute particles of dirt would act like sandpaper and grind the seats and valves away. This is the whole reason I like my engines running a tad rich than lean. It helps keep things cool.