Update....Alas, Nirvana, Net. The #78 SN I was informed the gun carried was actually part of the importer's log number (sigh!!) and the gun's actual SN is of the more common "C" variant... C-33613.
The gun is still slathered in cosmo as I just picked it up last evening, but the wood appears to be in very good shape and is a rich dark reddish-brown with a couple of minor dings here and there and some light indentations under the bolt handle from being shipped in a crate without separators. The hand-guard is of a slightly darker wood than the stock, marked with a now barely legible part number, and appears to be original. However, the stock had been replaced and has the usual 1.TRZ on the right, a partially double struck SN on the left, and the only other markings I can discern through the cosmo is a very small circled "BK" (probably in Cyrillic) on the bottom just in front of the sling swivel and an empty partial circle of the same size about 1" in front of that.
The receiver and bolt carrier have been force matched with an EP during a refurb and I have not taken it apart yet to see if the barrel has been also-- The bore is in pretty good shape; some specks of cosmo, but no evidence of pitting or rust and the rifling remains well-grooved. So, while this SKS has obviously seen some action following it's refurb, at least the barrel was well-taken care of. The bluing is original and appears about 90% on the rest of the metal parts.
The receiver cover has a higher serial number (624797) from a run that post dates the build window for 59s, so it may be representative of the transitional period between the end of the 59s and the start of the 59/66s. The mag cover looks like a replacement and has just a part number and the trigger guard appears original.
So, while this is not the collector's gem I thought it could have been, it is a true Yugo 59 LB in overall good to very good condition that can be shot without guilt while still filling a niche in my Comblock family.