For something that's sat a while, but runs, you can try to fill the cylinder with a product and let it sit a few days. Mystery oil, Seafoam, whatever. You'll need to change the oil afterward though.
If the rings and ringlands are dirty, it may clean those enough to so the rings fully seat and it may cut down on the smoking. The valve guide seals get hard and maybe riding it for an extended time will soften those up, a little, but it won't fix anything. Maybe all just enough to cut down on the smoking.
Otherwise, just ride it and see what happens. A little smoke at startup isn't a big issue to many people, as long as it's not being a big oil user and fouling plugs.
If I pull and engine down, it's likely to start a runaway project that gets a bit over what I intended at the start. Basically, every little thing I notice wrong is going to get some attention, even rusty bolts. I can't hardly just pull one down for a top-end job and put it back together without making it evident I put some time into it.
The story of three wheels and a man...