This post is based on the assumption that where oil seal retainer meets the engine block contributes to leakage at the points of contact, between the block and the retainer this might not get a proper seal
. Would it help to cut the rope seal that goes in the block short and the rope seal that goes in the retainer long so the seam of the rope seal would higher than the contact points of the block and the retainer.  
just a thought while I was assembling the engine.  A person could put one part of contacts points on the seal staggered which might help slow down the leak. 
Let me know what you think.  Larry

Larry