Engraved Ruger Blackhawk Worth?

Wanted to see if you guys could help me get an idea on what this gun might be worth. It is a stainless Ruger New Model Blackhawk in 357 and was manufactured in 1977. Ruger made an engraved gun in 1976 called "Liberty" but I haven't been able to find anything similar from '77 so it must be a custom job. What puzzles me is that it has the Winchester logo on the grip. Makes me think it was some kind of commemorative piece but I don't know why Winchester and Ruger would be linked on a 357 Blackhawk. Tried calling Ruger but they were stumped. Said I could send in $10 and get more info on the gun but I figured I'd try here first. It's my stepdad's gun so I'm not trying to sell it but I would like to tell him what's it's worth. He's had it for over 20 years and he's never shot it. It just sits in a closet.

Custom engraving and I believe aftermarket emblem that someone put on at some point

Just a guess, but maybe it was sent to the Winchester Custom Shop for the engraving?

BTW - It's very cool.

Maybe it was engraved for a USRAC exec, or something like that.

Doubt it's factory. The letter is worth the $10 because they'll give the model number and ship date too.

The best thing about is it's a very early stainless gun but for most people the engraving devalues it.....unless it letters as factory (once again, doubtful).

Very cool, sorry thats all I got...

Not a clue on value , but very neat gun.