If you are interested in doing your own historic research into the McCulloch family, explore these free sites.
People of Medieval Scotland provides transcriptions of original medieval documents, such as the Ragman Rolls. Available records include early references to Thomas, Michael, William, and Gilbert McCulloch.
Archive.org is a free database of various books and records. The searches are not intuitive. So, spelling matters. Be sure to search using various spellings including M’Culloch and McCulloch.
Hathitrust is similar to Archive.org, but not all documents are searchable. You may have to find an index to longer works, then identify the page or pages of interest.