Ok, while my 1979 911s is running smoke comes out, not much though.
It has a smell, almost like burning oil. It's been sitting in the driveway for a good few months or so. Any help is appreciated, thanks in advance... I'll answer any questions.

 

OK, a few questions:

* Is the smoke coming out the exhaust or from under the engine or from the top of the engine or ??

* If you remove the air filter, is there any oil in the airbox?

* How many miles are on your 1979 911?

* Has the engine top end ever been rebuilt?

* Has there been a compression or leakdown test done in recent memory? Results?

* Was the 911 sitting for a few months for mechanical reasons?

 

Just a hunch....
If you're smelling burning oil in the cabin, you may have various leaks that are ending up on the heat exchangers, and then, burning.