For references to less known chans: 
https://allchans.org/

The other chans are sure one of the possibilities as to where to find people interested in this board, but other chans are not the best places among all existing options, I think.
The best places where to find potential new people interested in this board, are the bigger social medias, where there is censorship, ostracism, misdirection, bullying, or general hostility anytime one talks freely about their faith.
Since here on endchan they can find the freedom of expression they are denied elsewhere.
Endchan boards are harder to censor (but really all chan boards are less censorship prone), and so long the rules of the board are upheld, all the hostility and usual attacks, can be contained. (differently to how in most social medias, the hostility and attacks not only are not penalized or reprimanded, but they are almost encouraged)

Though, trying to give visibility to a chan board on mainstream social medias, will almost surely lead to bans, and quick censorship. 
So one should be prepared beforehand with trashable accounts, and just rely on that short timeframe of visibility, before the notice is removed or hidden. Even in high traffic pages, it still takes some minutes for moderation to move in to remove submissions.
Obviously public pages are better than private ones, that excludes places like discord or similar closed community sites.

Giving visibility on mainstream sites is sure more high effort, as those systems are designed to don't allow much visibility to normal users, but it may also make a bigger difference.

Just dropping ideas for anyone interested or willing.