Put a Speedy-Sleeve on that rear main seal surface and press on! They're available in virtually any size, and I believe that particular size is the same as a Ford Powerstroke Diesel. Of course, you could go ahead and get the back of the block machined for a lip seal and avoid the problem of rear main leakage altogether. I'm in the process of getting set up to do that little operation- - - -just have to get a surface plate reground and drilled to fit the back of the stovebolt block to serve as a mounting surface for my Van Norman boring bar.

Edit: SKF "Speedi-Sleeve" #99386 or 99387 will solve the pitted shaft problem. It should work very well with either a neoprene lip seal or a rope seal. Have your machine shop polish the seal surface down about .002" undersize and install a 99386 sleeve with LocTite. Problem solved!
Jerry



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