Leave it alone and bring it out every now and then to see if it will tell you it's secrets.
There's nothing you can do to that rifle to make it more presentable or valuable.
IMHO, it's not a shooter any longer. Especially if the lugs on the bolt and lug seats in the receiver are in similar condition.
Even the parts are worthless, unless you can find someone that needs rust pitted bits to complete a similar rifle.