Here’s my (unsolicited) view on your friends current combo......

The heads are the right “size” for the motor.
But the rest of the combo isn’t on the same page as the heads, so it ends up “looking like” an underachiever.
It’s really only an underachiever if you’re only focused on the heads.

With the current cam, compression, and induction, the power should be very very similar if it had been built using Indy SR cnc 295’s, and I’d expect the car to run about the same. It would have been a little cheaper to build.

What that SR combo wouldn’t have, that the current combo has is...... the potential to make noticeably more power......without resorting to a head change.
Sounds like that potential will likely not be realized unless the owner has a big change of plans.
Basically, with the modest CR and cam...... it’s a hot street/strip combo.
Hp/ci is on par with a 530hp 446........ and the overall characteristics would be similar.
It’s just scaled up in displacement........ with heads that are a bit overkill.

The other car with SR’s on the 572 shows what happens with you use small heads and a small cam on a big motor.
No top end power. It just runs out of air.
It sounds like it’s doing what one would expect a combo like that to do.

With the right combo the smaller heads can put up a pretty good number....... but it still will end up being rpm limited.