the 5513 is a great reference to have, theres a lot of experts and services available via the forum, as your Rolex hasn't cost you anything so any funds that you have to lay out to get it up and to a good wearable standard is nothing compared to the price you would have had to paid for the watch in the first place, the box and papers are also a plus,
my course of action would be to have it opened (by an expert) to see how the movement is looking, (post pictures) get it fully serviced, shop around and see if you can pick up a used dial and hands, the 5513 can be worn on a Nato strap and looks good.
do keep us up dated with this project and all the best you have a decent starting point.
all the very best "H"
