I am a daughter of a Calhoun of this lineage - the John Caldwell Calhoun (born 1832), son of Dougal (born 1806), lineage. This Dougal was one of the founders of the Alabama Presbyterian Church in Sibley, Louisiana.
There is also a John C Calhoun who was born around 1832, who is the son of Archibald Calhoun, the original immigrant from Scotland.
This is an older post though, so I imagine you have this all figured out by now; I just felt the need to add to it in case you had not.
Also, if you ever wanted to go further down the line with this branch of Calhouns, I could most likely help you out.