Hard to say what heads make the most power ....
The Eddy are OK but you have to check for core shift as they can be bad .
The RHS heads are supposed to be very good
We used the latest W2 heads & I was told that in stock car racing these heads are capable of well ove 500 HP with a 2 bbl carb but you have to buy everything to go with the heads , different intake , pushrods , valve covers , headers etc , very expensive .
W8 heads & a R3 block can make 800 +hp
Indy has an LA X head I think not sure what that is about .
THE arguement is if the alum heads actually disapate heat , one knowledgable person claims no but building a number of engines with alum heads & pushing the compression 1 point higher has never caused detonation problems so it must lower heat somehow .
As for air flow the engine is an air pump so for the engine to work better , you can create swirl in the heads for better mixing & efficiency , you can also close in 1/2 of the chamber causing quench which resists detonation , Also allowing the engine to breathe better should make more power as well . SO I agree just bolting on heads may not increase power & could lose power . Years ago when the eddy RPM big block heads came out my friend figured this was the best move to increase power from his 440 , , the valve were not in the same place as the stock heads to the pistons had to be fly cut for clearance , new headers had to be built for the angled plugs , the rockers did not center over the valve tip ,we had to use lash caps & correct pushrod length , there were a few other issues . We proted the Eddy heads & removed ported 452 Iron castings & went to the dyno , for the "low" cost of around 3k his gain at the wheels was 3 HP !!