If your going for maxed put engine yes ypu can make big power with ls style ehads. But ypu can get good heands for gen 1 engines. 18 degree heads make 800 hp without boost. And yes you canuse under cut valves in them as well as 23 degree heads.
But if you are talking about a 300hp-500hp engine. Gen one and ls will come pretty close to each other but cost for LS is going to be twice as much now there are still benifits but not always worth it in older ride.