How to build a 13 second 340 Duster

I see that's the new price for a pair of these (around $630 apiece).
I'm guessing there is definite advantage to these over the stock J heads and if that's the case, I'd pay something extra over the price of rebuilding mine.

I'm not sure why you're saying have them checked since they're new.

I'd like to learn more about what the actual advantage would be. I understand an aluminim head allows for more compression without detonation (I think due to better heat transfer?) so this alone is significant. I could not find actual flow numbers for these or the stock heads but I'm guessing these may flow better since the ports are machined.

I assume I can use the stock intake and rocker arm setup so I'm not forced into buying more parts to go with them.

I wonder about durability.

I've had it in my head that I'd like to pick one upgrade from the stock setup where I can transfer rebuilding costs into the upgrade and this would seem to fit.

I appreciate the help I'm getting, and hope I'm not asking too many questions!