Turns out the bolsters are by Rex Pedersen, well known firearms engraver. Here's his note back to me:
John,
I hate to admit it but yes, that is my work. EARLY work..
I'm guessing it was probably engraved around that time as well. Of course I was proud of the engraving when I did it but I have improved a lot in the last 25 years!
To be honest, I have no idea who I engraved it for however. It might have even been a spec knife. Back then we had a larger retail store and had quite a bit of scrimshaw items. I might have purchased the knife, engraved it and sold it but frankly, I don't remember.
Hope this helps,
Rex
Rex C. Pedersen
Firearms Engraver