okay, here's a couple ideas about Ruger Number 1's and the 7x57 in particular.
The #1 7x57 has a checkered history because of the original barrels Ruger used. They are throated long. Group sizes are negatively affected, and 3 inches at 100 or Greater are common with anything less than a 175 grain round nose bullet. Even the 175 round nose can have issues with large groups due to the overly long throat. Once Ruger went away from buying to making their own, this particular issue ended. I've passed up a few for this reason.
The thing is, the older Number Ones had better wood than what Ruger has put out in the last 5-10 years. Ruger Number One wood holds it's value, as do the Number One action and other assorted parts. Just not the older, long throat 7x57 barrels.
That being said, the custom work will have to be valued on it's merits and if not done by a Recognized engraver or stock maker, and with corroborating paperwork, then it's only of value it the buyer likes it enough to pay for it.
Check in with a fellow on Rugerforum.net that goes by El Numero Uno.
He will know a lot more.
A NIB Ruger Number One up here will go $1100-$1200, used in very good condition, $800-$900 depending upon desirability of chambering. An action, about $400, wood, anywhere from $250 to who knows what depending upon figure. Good glass holds value and 50% less than new is very optimistic on the part of a buyer. More like 75% of new cost.
BUT, without pictures, it's all guess work, so here is my guess.
For the rifle, Id offer $900, the scope $600, and if she said that was too low, I'd counter with $1000 for the rifle and $700 for the scope. If she wanted more, I'd shake my head and say it's not worth that to me and walk away. There are more 7x57 Ruger Number One's out there that can shoot lighter, spitzer bullets for less money. and I've never paid more than $1125 for a new one.