camshaft for 225
You want rpm or power ? You can spin the engine way past where it stops making power especially if you upgrade valve springs.
head flow has more to do with how much useable rpm you can have. A 285 cam with. Stock 318 heads vs ported W2 is gonna have way different power bands even though the same cam.
stock /6 head or even ported don’t flow to well, you’ll have a hard time getting high rpm power out of a 225.
what kind of performance you looking for ??