The 302 will flow less because of the even bigger bulge in the intake port caused by the pushrod hole witch is larger because of the PR angle in the roller motors. How much is anyones guess , no one really runs either of these heads in a build that can afford a flow bench.

I would not worry too much about the hardened seats myself as I ran a 68 273 for years beating the crap out of it 85 octane no lead and the seats were fine when I finally tore it apart, as a matter of fact I see worse seats on a lot of the magnum heads than any of the older non hardened seats. I have heard the reason for this is the mopar heads have more nickle in them than the other makes and it helps with the receeding seats.