A friend of mine years ago, put a good dual exhaust system on his car and a good quality open air filter. We dialed it in the best we could with the tools and knowledge we had at the time and his car ran great for a 318 in a 1970 charger.
IMHO 318s get a bum rep. The cam was/is their problem, the same as the Chev 305 and Ford 302. Yes the 318 has smaller ports and valves than a 340, but they respond well to inexpensive mods and will run for a long time with a bit of TLC.