Heads, which ones when....

Hello Experts
As always I come here open minded but broken hearted...
Yet, still hoping for correct minded advice and help.

Now I know this is going to be a result of "preference" but can there be a good way/proof of what is the better if not the best small block head one can use on an engine already producing about 350-400hp (without the bottle)
Is there an aluminium style head that if one was able to obtain no questions asked, would we all go and buy ?

Thanks.
MAPS

PS. If there is a need to know certain things please ask and I will reply.
340 Formula S Barracuda A Body, 4 speed, 4.10, Caltracs, mono leafs.
10.5 Compression, 550-575 lift cam (Solid, mechanical) 6 bbl induction.
Headers Hooker Super Comp. (Adjustable race headers)
Thanks again...
Just so I'm understanding you correctly, your current motor makes 350-400hp and you want to upgrade, correct? Also street only, correct?

What exactly are you looking for (HP #, or ET#)....it is easier to make a suggestion if there is a specific goal in mind. All engine parts (the combo) need to work together to make the most of them, which is why I'm asking.