There are actually two different MacCulloch tartans. The older of the two is the same as the red MacDonald of the Isles tartan. (I'm not sure why this is -- the MacCullochs were associated with the MacDonald clan -- but the STA does show MacCulloch as an alternate name for this tartan).

Then Peter MacDonald designed a MacCulloch and a MacCulloch dress tartan in the year 2000.

The name is associated with Clans MacDonald, Ross, Munro, and MacDougal, so all of those clan tartans are also possibilities.