As the title says, which head for a street car? It’s going in a Duster for some old guy fun. Hopefully 350- 400 horsepower.

Good time to be doing a small block from a head perspective!

For max OGF, I'd recommend the EQ Iron Rams if your project is Magnum based or the Indy iron heads if your going LA. They will get you where you want to be out of the box if you're in the 9-9.5:1 CR range, and with a cam that will work will well with a stock converter. And you'll be able to really spend a lot of money on tires. You can easily get more with bigger valves and more cam. They have a closed chamber and there are lots of piston options to get you to where you want. Heavier but cheaper than AL.

I did a Magnum 408 with a 230/.55/110* class cam from Hughes, a 2500 stall converter in a 904 in an E body (750DP, RPM Airgap, 1 3/4 Super Comps, 2.5" exhaust). I got the EQ's with the LA intake bolt pattern.

No real metrics to give you, but it is somewhere in between scalded dog and sodomized primate on my butt dyno readout. I've spent a lot of time drivability tuning, but da Kovid botched the club days at the track where I was going to tune this spring.

In all honesty though, you could probably get there with a good valve job on a set of either 308 or Magnum castings given your goals. If Magnum though, it is probably easiest and less brain damage and not much more money to use new castings. In my searches in the yards, I found 1 head on 6 engines that didn't have cracks between the valves on at least one cylinder.

Have fun!

The old Magnum crate motors from MP, at that level, were essentially a stock long block with a single plane and a cam swap.

As mentioned, a set of magnum heads on an LA block will do, but you will need to deal with compression ratio (lack of that is) using an LA shortblock. If a rebuild was already in the cards then it's not really an issue.

Iron heads at around 9.5:1 are pretty close to detonation on the street in my experience.
(That's with a reasonable cam that isn't bleeding off CR (and low-end torque).
If it doesn't have to look OEM, I'd run aluminum heads, which are better pretty much everywhere you compare.
Paint them & the intake engine color and most folks won't catch it.
It also never hurts to take some nose weight off a car.