To find a reasonable estimate, you'd need to know the specific options on that particular CJ-7. Even then, it's an estimate based on similar vehicles and general guidelines from the era. You should never rely on an estimate for safe towing.
Generally speaking, a 1979 CJ-7 with a standard engine and transmission could likely tow a small trailer (maybe 1000-1500 lbs), but this is a very rough guess. Heavier engines and heavier-duty axles would increase this capacity, but likely not much more than double that. Anything heavier risks overloading the vehicle, damaging the drivetrain, and being unsafe.
To determine a safe towing capacity for *your* specific 1979 Jeep CJ-7, it is crucial to consult a qualified mechanic or refer to any available original owner's manual. These sources may provide more specific guidance based on your Jeep's build sheet.