Mark, IMHO, If the car is a series II and stock twin strombergs, a couple of things come to mind.
IMHO.
1. Electronic ignition, smoother running noticeable improvement, better burning of fuel.
2. NGK plugs, The original Champions are now made in a sweat shop in Mexico, they stink. Open the gap up to 5 degrees if you like , after the electronic ignition, play with it till it feels good to you, I open my plugs a couple degrees. Or leave it stock.
3. Even for the compact air cleaner on series II K+N makes a filter for it. It will run 5 degrees cooler IMHO.
4. Adjust tire pressure to around 30 lbs, if your running modern stock height radials. If running bias, all bets off.
5 Front wheel bearings, Make sure they are greased, freed up and not binding.
Five simple steps, to a smoother running car, without spending a lot of cash.
Try some of them, I think you will like it.
GOOD LUCK.
GTJOEY1314