Which brand of aluminum hemi heads are you using? When you took the motor apart to replace the lifters did you see oil in the intake ports or not? Oil comes into the combustion chamber several different ways, intake gaskets sucking oil, valve guides, rings or maybe sometimes from PCVs I feel for you, I've fought that demon more than once, that is one of the reasons I commonally call them Hemiroids motors, they can be a big pain in the rear smetimes BTW, all the problems are fixable, once you define the problem correctly