8) save your money and dont worry about adding hardened valve seats as they are not needed these days. while lead has been removed from the fuel, there is a lubricant that has been added over the years to lubricate the valve seats to prevent seat recession. as for the compression ratio, you can machine the head to get the ratio up, or you can go with the turbo, i would use an ihi turbo from a later model tbird turbo coupe. keep the boost pressure below 10psi and you are good to go with a stock short block. otherwise get your compression ratio up to around 9:1. since you want to improve fuel economy, i would go with a slightly larger dual pattern cam available from classic inlines. pick on that works from off idle to about 4500 rpm. swap to a good electronic ignition as well.
by the way, the advantage of the later head is going to be better airflow, though not much better, and larger valves.
