these heads i'm working on came off a 13.5:1 422" motor.
this particular build is definately a combo thats got a few shortcomings.
its in an early A body with like 1 1/2" primary tube headers for one.
it had a long duration aggressive flat tappet cam in it that i felt was really just wrong for the car, so thats getting changed to a roller.

the intake bowls on these heads have been enlarged slightly under the valve seat insert, and are already at about 93%.
they also left a little ridge at the bottom of the insert where it meets the casting.....and the bottom "angle" is about a 12mm radius off of the 45 deg seat.

i'm going to put a 2.055 intake valve in to get the percentage a little lower, and give me some meat to play with on the valve seat.

i'll post some numbers in the next couple of days.
as i said.....if i can just get them to not really take a dump after .500 lift, i'll be reasonably happy with that.
i dont have a race type SB intake at the shop, but i'm sure using it would "cure" the high lift issues.

Brian, as for the chambers.....the results you got would indicate that some chamber mods arent necessarily the kiss of death with these heads, but i think with a "better" initial shape of the chamber to start with, especially right off the seat, these heads would be less time consuming overall to get the kind of numbers you got out of them.
on some heads the flat roof doesnt seem to really be an issue(BB Mopar E heads, stage 6 heads), but on others.....they need that chamber wall in closer proximity to the valve.....especially as you get nearer to the seat.

if one were to have a scrap head to play with, it would be intersting to epoxy up one of these chambers and start from scratch, and see what happened then.

one last thing, since you have found the pinch area is a big player with these things......i guess that would bode well for the Indy-Brocks.....since it can be eliminated on those things.

maybe an Indy-Brock type head, with a "real" chamber, and true W-2 style exhaust ports might be a nice little unit someone should start making