You are
Correct to a degree. The standard port aftermarket heads are still considered a stock replacement head and as such, they only obtain so much power. And a good bit of it they make. But only so fast you can go. Now you enter the Indy, W series heads.
Your wondering if you’ll feel or notice they extra 15 cfm?
Are you lifting the valve that high?
If not, then don’t bother.
Are you racing the car or is it still mostly street?
If it is not a light weight race ride, then don’t bother.
Are you going to take full advantage of the upper level head?
Of not, then don’t bother.
FWIW, your cam is listed at 260*’s @ .050.
I call that a small big cam.
You also never mentioned the cams lift or the rocker ratio along with the current head flow specs. Without this information, were kind of shooting in the dark to get you out of the dark. You want out of the dark, you need to turn on some more light onto the situation with complete information on your set up.
Also, (not breaking balls, but) your car is really heavy to realize any gains from more advantageous parts. Bust that heavy girls gut down to sub 3K.
Less weight is faster and less broken parts.