71 GMC with 454 Burning Oil !! Can you help ??? Please !

[jeremy_phd]

I have a 71 GMC 4x4 that I just put a 454 in. It later just started smoking and we thought we figured out that it was just one cylinder. It only smokes out of the passenger side tailpipe and it only smokes when you are ideling. If you hold the engine at say 2500 RPM at a dead stop it doesn't smoke but as soon as you let your foot off the gas and the engine returns to idle speed it comes out again. And when you drive it down the strett it doesn't smoke either. The only oil it uses is at startup sometimes and at idle all the time. We took the pass side valve cover off and found that one of the cylinders had a broken valve seal and we replaced it and all the other seals on all other cylinders were fine and unharmed but aftre this it still does the same thing and smokes only at idle and only out of the pass side. We thought it might a vacuum problem and that it might be suckin oil out of the intake valley or something but I'm lost and I need help please. Anybody have any sugesstions or help I can use ?????