It is a very cool find. I'd as well leave it as is, sort of. Outside, clear lacquer or "Eastwood Patina Protector" (google it). I'd also consider, because it's so fragile, "filling it". Using a very, very, easy release tape to cover the holes. Then fill it with something along the lines of plaster of paris. Even mix some dry colorant into the plaster, dark reddish brown. When it's cured, pull the tape off. Your not going to ruin the tiny collector value and it'll be a lot more resistant to damage. Maybe even melted wax.