71 Dart Steering Box Leaking

You don’t say exactly where it’s leaking from or if it still steers well so there’s a lot of assumptions that can be made. If it’s leaking from the sector and or pitman shaft those seals aren’t all that hard to replace. If it’s leaking from the power steering hose connections those O rings are pretty easy to change out. If it’s leaking from the power steering pump it’s also not very hard to rebuild and reseal.
If it’s still steers good and you’re happy with the way it performs I’d definitely look at repairing the leaks.