ye old oil burn

So the oil burning is slowly getting worse...
Only does it when idling for a minute or so then starts poofing smoke. Go to take off and shoots out a cloud and that's it. No smoking under load at all. Engine runs great, loads of power. Especially when its like 20 degrees out oddly enough. Seems DCOEs like cold weather... who knew?
I am convinced the valve guides are the culprit because I know for a fact they are worn bad, BUT I am wondering if the smoke could be blow-by. I dont have a PCV system at all anymore. Only reason being is that I dont really have anywhere to hook one up at. The black box is just open and vents to atmosphere. Is it possible that because there isn't vacuum on it, the fumes just aren't venting and are building up in the crankcase then being pushed out past the rings? I'm at about 295k miles so pretty sure the rings dont seal as well as they used to.
I found a rebuilt head and some other parts so I was working towards rebuilding the entire top end. Maybe I should just go ahead and do the entire engine at this point..

Are you sure oil isn't dripping off your open black box and onto the exhaust pipe?

Thought that too, kept an eye on it for a while but doesn't look like any oil is coming out of the box.
Also, where the header leaks, it'll poof smoke there so I know it's being burnt internally.

Do have a thought to build a pcv system though...
Figure out a way to route a line from the box into a catch can then hook the can up to a port on my vacuum manifold. At least that way I wont be pulling things into the manifold clogging it up and should keep the returning vapors clean going back into the intake. Also dont want anything being brought into the megajolt unit since that's hooked up to the vacuum manifold.
Really the only hiccup is mounting something to the black box.

A compression test will tell you a lot. A leak-down test will tell you more. Beyond that, I always try to fix what I know to be broken before looking for additional possibilities. Compared to overhauls, valve guide seals are cheap and easy so ...you know.

As for the black box, wouldn't it be easier to repair it than to re-engineer it?