gibson guitars hummingbird

Can someone give me info. about this guitar?
My grandad gave me a guitar, and claims that at one point and time it was a Gibson Hummingbird. He had it refurbished in the 70′s at a Steel Guitar shop in Nashville, TN. Anyway, the paper in the guitar doesn’t say Gibson, but another name. Is the guitar still worth anything? Also, is it possible to refurbish a guitar and completely change the name of it?
If it is an old vintage Gibson then a refurbishment would knock it’s value as it’s therefore not original. You could do many things to “refurbish” a guitar, strip & repaint the body, change the electrics & pickups, change the hardware etc etc. Of course it’s also possible to change the name on the headstock. People normally do it to try & pass the instrument off as a better version though, eg. changing the name on the headstock of a cheap far eastern strat copy to read Fender. What’s the name on this paper?
DARRELL SCOTT | Hummingbird Guitar