remember, i'm no engine builder.
however with that said, i have seen countless recommendations to fill the side areas with silicone "adhesive".
another tip to do with the rear seal retainer is drill out the bolt holes a size or two [depending on how the block threads are positioned and the seal retainer holes are drilled] to allow the retainer to center the seal on the crank, and thus the bolts can be tightened without moving the seal to one side or the other, causing the seal to be deformed.