Yes. That splutter/chuff/pluff sound is a single-cylinder misfire. A less primitive ignition system, aside from its other benefits, will likely reduce or substantially eliminate the misfiring—
HEI upgrade with attendant upgrades to the spark plug wires and a carefully optimized distributor cap and rotor (per the suggestions in
this long (but worthwhile) thread).
But keep in mind we are talking about a car most of 50 years old, with a not-very-well-designed carburetor known, especially in its first couple years ('74-'75) for poor mixture distribution. If the only symptom is the audible misfiring, you'd be perfectly well within reason to just quit putting your ear near the tailpipe.
