Aluminum heads $ per HP?

To just throw some numbers out there......
Depending on how well the stock heads are done, and how good they flow, along with how well the particular set of new heads you end up flow.........and then there’s still the cubes of the build........I’ll say.......

Unported “RPM style” heads:
340/360 - 20-40hp
408/416 - 25-50hp

TF heads:
340/360 - 25-50hp
408/416 - 30-60hp

Assuming the stock heads were at least “pretty good”.........With the low-ish lift cam and VS carb, I think they’d all end up showing improvements nearer the lower end of the range....... and even that might be a bit optimistic.

The heads have to be what’s holding the combo back before you’ll see big gains(or any gains) from swapping them for something better.
It’s always about the complete package.

Two street pump gas 360’s on the dyno here last year.
The one that was the better overall combo made about 80hp more than the one that had the better flowing aluminum heads.