make sure you want to spend the money. you can buy 245 cc AFRs, 340 CFM can put you over 700 horses N.A. Which 18 degree heads were you considering?
My 227 heads after cleaning up flow 327 CFM.
what is a little more power?
what size headers are you using now?
you can use a bigger carb
you should step up that cam,,,a lot