318 mystery problem, somewhat solved!

If that's actually all oil smoke, your O2 sensor will have fits! Has the engine always used oil? How much (miles per quart)? Is the sensor a 1-wire or 3-wiare (heated). Where is it mounted in the exhaust system? You could be running so rich that you are having oil dilution from the cylinder walls. But any engine running that rich probably wont want to idle smooth.

If your MSD is "buzzing" something sounds wrong. You probably should go over the changes you just made right before this began happening. I hate to say it, but it sounds like you may have made something worse. The MSD box will stop buzzing when it fries internally. Not sure how long that will take, but it can't be good to keep running it like that.