Well I would imaging a 45 years old crossbow is a fiberglass recurve bow and I don't see why he couldn't shoot it still. It's not going to dry out or anythign else like that. My recurves are 50 years old or more as I inherited them.
I used to make strings for my selfbows that we 12 stand (6 wraps) and serve them. Then i tied knots in them until they fit correctly and measured it and made a proper one. Maybe there is a better way, but its the way I learned being self taught before YouTube.
