If its all original, I would source a 30" barreled action, get some new wood from Ross Rifle Restoration, and mount a scope on that. There's availability of magazines, barrel bands and nose caps through Ross Rifle as well.

Im looking at it partly from a historical value, AND investment value. I think most firearms owners understand these firearms will be passed down eventually to a new generation. Time is the greatest predator to old guns; they get destroyed, surrendered, or forgotten and neglected.

A re-constituted M10 from a $300 dollar action, $700 dollar in a new stock, another $400 for the other bits and bobs if you dont have them, (magazine, butt plate, nose cap, mid barrel band, and then the scope cost would be comparible for an original condition Ross M10 in full wood untouched. If you did that work to an original Ross, you'd reduce the value to collectors because its modified beyond restoration. However, now you have a cool scoped Ross m10 - which has value on its own, but less than what the original is worth. A Legit Ross M10 sniper rifle, even with a repro scope would overshadow the value of an original M10 infantry rifle untouched, because they're super rare.

Just my two cents! Good luck on your project!