Rebuilding a 65 273..I need some help.

1.500 exhaust valve. I think MoparOfficial ported some heads for someone, Seabee? At one time they might have been available for purchase?

Ok. I started porting heads back in HS for my shop teacher who was a serious drag racer. I still have a nice hard seat grinder kit and an old Sioux valve grinding machine. I have been porting mostly BB Mopar heads. So I'm not new to porting, Not a pro either. But What is it about SS valves that prevents you from needing hardened seats? I have never heard of this.