Welcome, and congratulations on owning a B body Mopar. Though this is an A body site (and I own one, a 72 duster), I prefer my B Bodies (68 Sat, 73 RR). 318willrun has some good advice. Having said that, I myself wouldn't put any money into a 273. Too small, especially in a B body. Even a puny 318 has a 40+ cubic inch advantage. I would save my pennies for a big block. B motors and B bodies go together like PB and jelly. Even a worn out motorhome 440 will run rings around a mild performance built 273. Sticking with your current engine, a stock 4v intake will help, as 318wr has mentioned. Performer would work also and is pretty common . Any small 4v if working correctly will probably be an improvement over your stock 2v. Bang for buck stuff: Dual exhaust if not already equipped. If the cooling fan is solidly mounted, switching to a clutch fan or electric fan would help performance and fuel economy. Distributor recurve is cheap (free if you are just tossing the heavy spring). Cold air to the carb , either by a hood scoop sealed to an air pan, or ducting going from the air cleaner housing to outside the engine bay( under the bumper for example.