Can not help regarding rifle's value, but will comment about the cartridge - 7x61 Sharpe and Hart. Was developed by Phil Sharpe as an "ultimate" hunting cartridge - he based his design around IMR4350 powder and 160 grain bullets. Only ever factory loaded by Norma, I think. After Phil Sharpe had passed away, and Remington had introduced their 7mm Rem Mag, Norma re-engineered the brass - different (better?) brass or heat treat - kept the exterior dimensions exactly the same but made more room for more powder inside by thinner walls and shorter internal cartridge head. Did not actually catch up to the 7mm Rem Mag - about 100 fps short. Most commercial rifles were made by Schultz and Larsen - many with 26" barrels, so real muzzle velocity likely identical with 7mm Reg Mag which usually came with 24" barrels. The original Norma 7x61 brass will be head-stamped 7x61 S&H Re, whereas the newer stuff by Norma is head-stamped 7x61 Improved. Both can be used in same rifle; hand loader needs to know there is about 5 grains capacity difference between the two versions of brass.
I had worked a few years ago with one - original ammo that friend had, turned out to be Norma 160 grain Triclad bullets; last time Norma loaded this round, they used 154 grain bullets. We re-formed a number of R-P 7mm Rem Mag brass into 7x61, and loaded with IMR4350 powder and Hornady 154 Spire point bullets - buddy took a Sask. farmland moose with it that fall with a single round. Apparently, you can tell original Norma factory because they have tiny "NP" embossed on the primers - Norma's reloading primers did not have that - NP on the primer found only on factory ammo, I was told, here.
I received a Schultz and Larsen Model 60 in 7x61 S&H for myself from the EE a couple months ago - still fussing over scope installation, so have not fired it yet. Was able to accumulate some factory ammo and decent supply of Norma brass. Have been stockpiling 154 grain Hornady Spire Point for a couple years, in anticipation.