Hi Deejay & Grumpy
I managed to get hold of the gentleman I purchased my SB from, unfortunately he was not the original owner of this craftsman.
He has had it for the last 15-20 years and unfortunately did not get any paperwork when purchased from an elderly couple.
The only info that I can really pass on is that he has not replaced any major components since he has had it, but obviously that does not provide the info required being that this is not proof that this was the original engine.
It sounds like it is but unfortunately no documents to prove it.

cheers
Watson