I remember in the early 2000s people would have been disinterested based on the heads. Since then it's become more widely known the potential of the iron heads. When you hang around long enough you see tides change.
There were arguments about airflow being enough or not and then it went to port size and RPMs. A lot of examples were, again, lifeless after 5200 rpm..but iirr the cams were 240's @.050. The better AM iron heads still only averaging around 495-520 hp according to x dynos testing at the time. That's just the stock push rod location stuff now.. I don't mention the others because it's not really relevant to what we're doing and it would also take it off the rails , again.
So in the right hands 500 hp isn't unreasonable at all. In the average garage mechanics hands.. 420-440hp is what the few examples have shown us.. with 240'
[email protected] 110 lsa camshafts and around or a tinge above .495-.510 lift.
Look at some combinations, 4-in Stroker with box stock edelbrocks and remember they flow w/2.02 in the 240s cfm @171 cc's..x2=480hp and will probably RPM a little more with the exhaust Port working better if testing with the same camshaft and combination of parts with only the head swap.
Stock head are around 160cc flowing w/1.88 around 212-216 cfm x2 good for 420hp .
So what's the goal?
Max efficiency to squeeze every bit of horsepower out of less effort... or Max effort for big power by pushing the casting to its limits...
You can work 250 CFM with a 1.94 valve with substantially less effort than using a 2.02 to get to 250 and less shrouding. And even larger valve would get you more power of course with more work. Depending on what intake manifold you're using...it can be insurance to push a little further than the goal for any lacking in the intake, though there shouldn't be if you use an m1 or vic340 intake.