Limits of an Edelbrock performer and 1405 600cfm carb

It all depends on the combo of parts and usage. In a light car like you mentioned, an Edelbrock 600 and Perf manifold, when combined with Magnum heads(an upgrade on LA), and a sensible cam around .525" lift will get you 325 HP even with factory logs. It will be fun street engine that will be a good daily driver.

If you havent "built" the 318 yet, consider using a 5.2 instead as they are super cheap and work great, have roller cam etc.