Is this worth it? 1974 440

You should use the water pump housing from the 383, that housing on the 440 is a truck only piece and you'll end up with a pretty weird lower hose, if it'll even clear your K member. Also lose the MH exhaust manifolds.
Other than that, you might be perfectly happy with the motor as is though an RV style cam would be a nice upgrade and easy to install while the motor is out.
While the late 440s are way down in power compared to the earlier Magnums, for your intended use and in a light car, it should be fine.