Closed chamber heads for 273 in S. Calif.

Yes, 302's would be nice. Of course they cost more too.
What's the full casting #'s for the ...646 and ...714 heads? Are those smog heads with egr ports? Did any of those have hardened exhaust seats too?
Since I don't have an egr on my '65, I'm assuming that those ports would have to plugged before milling that surface on the heads. Right?