Originally Posted by crazytown
The reason I am debating about swapping the heads out is because the heads on the 350 are the older type "fuelie heads" which are no doubt good heads for performance, but are made from the older engine technology for running on leaded gas. There is a risk of burning out the exhaust valves of old technology engines if operated with unleaded gasoline in heavy constant service. This is because old technology engines relied upon the lead in the gasoline to coat and protect exhaust valves from the extreme heat of the exhaust.
want to know what I'D do?
i'd run 'em 'till they needed a valve job,THEN worry about it.
what casting # on the heads?
if they have accessory bosses, chances are they've been induction hardened...