i concur with that assessment. from a porting perspective, it is not worth throwing good money at 40+ year old castings unless you are building a class racer. for a performance boost it is cheaper building w/ aluminum heads. that said it depends on what aluminum heads you are selecting. indy heads are not designed to bolt on out of the box (unless you buy the CNC ported ones). i have experience with the mopar and edelbrock non-raised port heads. the stealth heads are an unknown quantity to me -- other then what i have read on the internet.
on my street car ('64 fury) i have a set of mopar aluminum 452 heads (closed chamber) that are cast by edelbrock and are essentially the same as performer rpm heads but have straight plugs instead of angled ones. the only thing i had done was a valve job. they flowed at 273 / 195 @ .500 out of the box, which is perfect for my application. the engine is a pump gas .030 over 440 with an edelbrock performer rpm intake, 750 double pumper, 10.3 : 1 compression, and .508" lift / 247 @ .050 cam. the engine dyno'ed at 549 hp @ 5500 and 611 trq @ 4300.
the heads still have alot of potential if i ever decide to get more flow out of them.