Normally not a fan of restoring stuff, but as others have said, sometimes something is so badly degraded it only has "monetary" value if it is an extreme rarity. Really it comes down to what YOU want, if you are going to run it and enjoy it , why not restore ? It might harm the "original" value , but lets face it , unless it is a "rocking horse poo" rare model it wont be of any interest to a speculative collector in its current state 
If it were mine , I think I would be facing the same conundrum you pose and would probably do a light mechanical resto and run it , but I would always be considering a cosmetic redo as well
