I found the flathead six in my Rambler after a rebuild smoking more than I thought it should. I understand before it's broken in but damn this thing kept on smoking. I added "Restore" to it and it stopped after a little while, I don't know how long but all of a sudden it hit me that it wasn't smoking. I am not sure if it did anything or it simply would have fixed it's self with a little more wear or something. Restore USA - Engine Restorer FAQs
But you know what floors me, before I rebuilt the motor I ran it in the old parts car and it ran like a TOP, I mean perfect, idled like a watch, fired up in just a few cranks after 10-15 years in a bone yard, it really was a great runner. But it smoked like a mad dog and that is why I tore it down for rebuild. It had very little cyl wear and was in great shape, never really finding what was wrong to make it burn oil, just figured it was getting past the rings. I ran Marvell mystery oil in it for a while and it did nothing. Tried a number of tricks I heard about, did nothing. Well, I have to tell you, when I pulled out the fuel pump to have rebuilt I found that it was full of oil! It has a dual diaphragm pump so it pumps fuel and creates vacuum for the vacuum wipers. Well it is hooked up to a vacuum source on the head (the intake runners) and that goes to the pump then up from the pump is another hose to the wipers. I guess it uses the engine vacuum but then the pump keeps is constant so the wipers run smooth? (never did understand exactly what it was doing). So the pump had a seal that was bad and it was full of oil in the vacuum pump! There is a good chance that friggin pump was putting oil into the vacuum line going up to the head! That means my intake was SUCKING OIL into the cylinders and very likely was causing my smoking problem! I hate the thought of this after spending $2000 to rebuild the motor but I guess having it new is nice. But when it was smoking after getting it running I was pretty ticked at the thought that it may have been a good motor before the rebuild.
Anyway, you could give that Restore a try and look into your fuel pump to make a long story short.