I wouldn't get too excited about the so called "one piece" rear main seal. The problem isnt usually the parting points of the seal. In many cases its a poor finish of the seal surface on the Chinese stroker cranks. Also, AND THIS IS VERY IMPORTANT. If you are using tne replacement billet seal retainers cut some grooves in the retainer so that the oil can successfully drain back to the pan. If you install them you will see that the retainer winds up "shrouding" the #5 main cap and wont allow the oil to drain quickly back to the sump. The retainer that Best Machine sells is properly relieved to avoid this problem.

Also, the brown/orange "fluoroelastoimer" seal is the one to use. Its pricy at about 25 bucks, but I get no problems with this seal. Also, it should be a common practice by now to have a Chinese crank checked and corrected by a competent crank grinder before putting into use. Also ask the crank guy to check the rms surface. I usually have .005 cut off which tones down the heavy knurl they put into the rms surface.

MB