I would guess 99.9% of guys looking at a high end header like this don’t have power steering, so the fact they don’t work with power steering isn’t a factor
I dunno about that, I think a lot of the higher dollar pro-touring builds are probably in a power range that a larger diameter header would be beneficial and most of those guys aren't going to run manual steering.
Now granted, a lot of those builds are using modern engines too.
And what headers have you used on a small block? Because if the tubes are under the steering link they have less clearance than Doug's or TTI long tubes.