FoMoCo makes a tool for this purpose. I dont see why they want to go this route though! A 2 pc seal will work just as well if installed correctly....Did he tell you if the seal he used (the 2 pc) was a rope type or a rubber? The rope type must have a pin left in the block to pinch it into place. It will leak if that is missing. As far as the cam story, I think that is a load of crap. If the rear journal of the cam were out of round, you would get instability in the valvetrain. And exactly how
oil is supposed to gather behind the cam and push out the rear main is a mystery!
Having never seen your Windsor, I would bet that the wrong type of 2 pc seal is being used, or it is being installed incorrectly.
The lips of the 2 pc seal should NOT be parallel to the edges of the cap, and there should be a small bead of sealer on the edges of the cap. About a 1/16" wide in the corners or the rear main register and coming up to the edge of the
oil slinger. Do the same on the cap, stopping just short of the seal. Also, make sure that the seal is installed in the correct orientation.