The number of rounds through it really has no bearing on the value, as long as it's still got a good bore, throat, and chamber. The biggest factor in determining value is the percent original finish remaining, and the condition of the wood, to a lesser degree if the wood doesn't seem to match the rest of the gun's wear - for instance, a beat-up stock on a good-looking rifle probably means it's been reblued. ANY non-factory work or refinishing decreases the value considerably.
With Model 70's, you need to post the serial number, model, and grade to determine the value.... post it in the "Rifle ID & Value" forum and I'll get you a value.
The serial number will determine the age (and therefore the design) of the gun... Some of the M70 models were: Standard, Featherweight, Varmint, Westerner, Safari.... And they came in Regular and Super grade (Wood, engraving, jeweling, etc. made the difference)