I can't offer anything good on this. My car was like yours before I had the engine rebuilt, it ran great and it was had to believe something was wrong, except for the smoke and adding a quart of oil every 200 miles or so. My sons convinced me to have it rebuilt, nagged is a better word, calling me the polluter of Sugar Land. It's only a matter of time before you have to rebuild, may as well start saving your money for it.
1967 230sl (stick)