Cast Iron Toy Fire Truck

I bought a fire truck and four horses at a garage sale a few years back, It looks like it has been to a fire and not cleaned up yet. and I am missing the middle man. I have been looking all over for something to compare it too price wise. Maybe some one can answer the question should I repaint the white part of the toy where it looks burned or leave it alone?
The last piece I bought at the same time, it also has 4 hours it looks maybe like a cart for carring something to display but it would have to be heavy (only and assumption because it used 4 horses to pull it. It is a very interesting pieces