To help you a little further, from the Break The Bank 1970s edition, you typed:
The reason why Jack Barry hosted the nighttime version was because Tom Kennedy was too busy with Name That Tune.
I'm fairly certain Tom didn't host the nighttime show because he might have been competing with himself on some stations who played The $100,000 Name That Tune at the same time on another channel.
It is true, however, that Tom's plate was quite full as he was hosting NBC's 50 Grand Slam as well.