The 642 is a pretty easy revolver to carry and conceals easily. Holster selection is largely a matter of personal preference, but your physique, usual wardrobe, and normal activities should also be considered.
My website displays several OWB styles, and the "contact" page will get an e-mail directly to me if you would like to discuss specifics for your needs.
Lobo's products are very good, indeed; but if you want something off the shelf for IWB, check the Galco 158 series with j-hooks or the ActiveProGear IWB's...also with j-hooks.
Be safe.
Does anyone know anything about the Tagua for the S&W 642?