Great little heirloom piece you have. These are generically called sei tacche watches because of the six slots in the back. If you have the watch opened and take clear photos, you can post them here, but also enter the information on the Longines website and they will send you complimentary historical information from their archives. As noted above, if you plan to actually use it regularly, you would want to have it serviced, but it's quite a small watch (typical of that time), so be realistic about whether you will truly wear it. If not, just enjoy it for its historical connection to your family.