Otherwise you may find something of use to you here:
http://www.cbpa.org/members.html

http://www.keepingitcatholic.org/publishers.html

It is fairly unlikely that a large national house will express interest in his work unless there is something major that sets it apart from the pack. This sounds like a work well suited to niche publication. He is wise to avoid self publishing. That's a nasty little rabbit hole.
By the way, just as with any other publisher, he should not just send his work off to them. He needs to research their requirements and query them to see if there is interest, though frequently with small press there is less of a need for an agent than there is with the national houses.

Many companies are joining together though. Penguin Books is sucking up a lot of them, so try there.