Update...After having talked with ATF and my local PD, numbers ran, photos, etc, the consensus is its completely legit to own. It appears (as mentioned by Tom) the SN has not been obliterated, only a suffix added, which does not interfere with the ID of the gun. I now have no reservations about either re-building it or selling it (with disclosure of this information). I have yet to dissemble it to ID the internals, but it should be interesting. Thanks to all for their time, opines and facts.
My new party trick.. I swallow two pieces of string and an hour later they come out of my ass tied together. I crap you knot.