Could be either valve seals or the intake. Hard to tell from a picture, but unless you bathe the top end with oil, smoke from valve seals tends to clear up pretty quickly.
I'd likely be looking at the intake first, but if using white teflon instead of Viton valve seals, I'd likely swap valve seals and check spring pressures at the same time. Been finding beehives can be all over the place in terms of pressure, bind, etc