You don’t have to try and find an existing cable tv channel to get many of these old shows. You can get many or most of them on the internet. Just get an HDMI cable and hook it up to your laptop or mobile device. Make sure you find the right input station on your tv. Usually it’s labeled for HDMI.
Say, you sound like just the guy my DH would love to sit with and ask numerous questions in order to get ‘up to speed’ as to how to make it work. At the moment he is attempting to bring two sites on the net (which we are able to view on our computers) over to the TV using Roku or just the Smart TV. There are two movie sites we would love to see in the comfort of an easy chair. It is all a learning process and like any other it takes time and repetition to develop the automatic skills and answer the hurdle problems.
Happy trails! :-))