I assume that your valve guide to valve stem tolerance is ok based on the guides being replaced with the new guides with clips plus your installation of new valve seals. Assume guides were done by a machine shop and clearances were checked. I also assume that based on the continuous smoking with CD2 that you added it as a cleaner through the carb. I have had good luck in freeing up stuck oil rings by adding it in the motor oil as an additional detergent. I have even used 2 bottles with an oil change. You might also try using a 15w40 higher detergent oil rated for diesel engine service for several thousand miles before changing. There is really no good way for removing heavy carbon and oil deposit buildup from the oil control rings except tearing the engine down and reringing it. I would try the double CD2 and/or diesel oil with higher detergent for a least another oil change period before tearing into it. It will take 1500-2000 miles or longer to slowly dissolve the deposits if it is going to.