Not a model 70 expert, but have owned a few, and like them. Unless re-chambered, it is almost certainly a .300 Holland & Holland Magnum. Final year, late production pre-64's were made in 300 Win Mag, but not many... Maybe 5000 I read somewhere. The year of your gun, and stock style argue against that.
The rifle appears in excellent condition for its age, and should be worth quite a bit more then you paid for it. Condition, caliber, and rarity are important in pre-64 model 70's.
That front scope mount looks like it might be a "Control" brand base, designed for their specific rings (Still in business). It could be removed, or the bases could be replaced with a different make / style of your choosing.
The dovetailed rear sight, as well as the front are available used, original from places like Gun Parts Corp., as are modern replacements that will fit properly, and basically look the same as stock.
If I planned to hunt the gun, I would definitely scope it, to take advantage of its accuracy and range. To sell to a collector, set up with just stock iron sights would be more desirable. Avoid "touching up" the stock or bluing as it will decrease value.
Larry