Welcome.
You needn't worry about spending every weekend in the garage to keep such a truck running. These trucks are quite simple and once running properly they need little attention save for the occassional tune-up.
You will need to spend some time at first checking wheel bearings, the braking system, and things like that, but they need little attention after that. Don't forget to install seatbelts, original or not. You might even want to go shoulder system too.
Should you do it? Check out what it would cost for insurance, taxes, and license plate for one year on a new vehicle, then do the same for the older vehicle.
If air-conditioning break downs worry you, perhaps you should think about having a retro modern system installed. However I would not expect problems from an old system once you get any small refrigerant leaks stopped. Again, simple is good.
If you go the route of the '65 I will bet that in 10-20-30 years you will look back on it as the sweetest ride you ever had. Hopefully you will wind up passing the old iron on to your children, and they to their children.
Best wishes for a great project with dad.
