Finally someone educated confirms my unqualified suspicion.
I played withso many 318's when I couldn't even afford a cheap gasket set that I lost count.
I always thought the 302 heads were too restrictive to be good despite the compression bump,and my amateur porting couldn't compensate.
My personal experience with these was using them on a bone stock late 70's 318 with pistons so far down in the hole I was shocked.
Even with the fresh valve job there was zero noticeable improvement.
Likewise the roller engine I pulled these off of had flat tops as close to the deck as I have ever seen on a 318.
This got a set of small valve j heads and a used racer brown flat tappet cam.
When the throttle stuck and I missed a shift the valves hit the pistons at 7200 rpm.
This was hardly an apples to apples comparison but one engine struggled to breathe by 5000 and I'd the other would have had good valve springs who knows how high it would have turned.
I grew up in an old school shop that was well regarded for Mopar stuff.
Many 318s went out the door with 360 heads milled .030,stock replacement 340 valve springs and a crane fireball cam.
I don't see the hype on these heads for performance.
Maybe fuel mileage.