Cheap 318 performance mods.

Heads are basically the number 1 component for NA hp especially streetable hp, look to the LS 5.3l same basic displacement, smaller bore not overly high stock cr.

In dyno trim (headers, tune, no accessories) stock cam makes 350 hp and with a 218 @ fifty cam well into the 400 hp range and most of that is due to the heads and still pretty streetable.

Good heads can still pass a decent amount of air thru an engine even with a moderate cam, duration is just the time frame air can pass thru head determines how much air will pass thru.

Saying that a stock 318 head can pass enough air for 250-300 hp with moderate cams, which is enough hp to get an A Body down the road at a decent pace. Like I said before don't have to do it all at once, can always do more upgrades in the future, enjoy it as you go one stage to the next.