bowhunt, normally refinishing a collector will downgrade value by a good margin. What you need to figure out is if you have a true rare M-70 that will draw top dollar from a collector. Or do you have a not so rare pre-64 M-70 that has more value as a good hunting rifle and would be a good one for refinishing and using it in the field.
Things that would make it or break it as a true collector is it a standard grade or is it one of the "Super Grade" models. What caliber is it? A very common caliber or one of the rare calibers that very few were made. You will need to do more research and make the decision to keep it original or refinshing it and get many more years out of it in the hunting field.
I have a lot of guns most not abused but with nicks and other signs or use on both my rifles and shotguns. It really doesn't bother me at all. I look at the wear and nicks as memories of great times in the field. The knick on the comb of my Orion occurred just after I shot my only triple on pheasants with a double gun. My .300 has some blueing wear from a memorable backcountry hunt with a scabbard that wasn't quite right. Now if I was looking to sell them I'd follow RELH advice. It depends on what you're going to do with the gun.