5.9 Magnum Smoking Badly

So I think the Magnum swap forum is the best place to put this, but the engine is still in a Durango. Motor is from a wrecking yard, from an 01 Durango, can still see the cross-hatching on the cylinder bores, but unknown mileage, don't know why it went to the wrecker. Has the EQ heads on it, stock everywhere else. Used the felpro 1008 head gaskets, and the car keeps smoking out the tailpipe, and is running a little rough. the oil looks fine, and so does the coolant. We've been fighting this for a long time, and can't seem to make any progress on getting the thing to run happily. Any help would be appreciated. If I forgot to include any details, just ask.