If you have .38 Special cases (they are very common, and likely can be found as range pickups.) just use them with .38Spl Data. Unless you load to the max, any data for cast bullets from 150gr. To 158gr will do. Don't go below starting loads, but you really don't have to load to the max anyway.
For black powder you need a softer lube. Big lubes are fine, but for pistols, they might not be needed.