Extra hp out of my 340.

In the US 1971 340 motors came with a thermoquad carb and intake that was pretty good to start with. Putting a set of good heads on it, or working with what you already have might be an effective way to up the power on the cheap. Find out what your current heads flow as is, and find out what could be done to improve them before throwing money at other heads that may not increase power without work done to them. Also check things like the timing curve, cam (stock? Not stock?) Is the heat riser passages blocked?