Ok so what all can be done to your basic 4bbl 305 chevy engine to get some extra hp's...

I am installing a 600cfm 4bbl carb
headers
2.5" exhaust with flowmasters (true duals)
K&N breather through circle and air flow top filter

is there anything else that can be done while I am getting it going to get a few exra hp's to the wheels?