I'm also in the revolver side for a shoot it once and it lives in the drawer for the rest of the time. A decent used Smith K frame with wadcutters, or 38 Short Colts for familiarization and wadcutters for leaving in it would probably work. I don't have any hands on with the SP guns to say either way. My first thought is a K frame gun may be easier to shoot and have less kick.
Bright orange fingernail polish, with a white base coat makes regular sights much easier to see.
If they can deal with an automatic, the Ruger Standard 22s are pretty simple, especially the earlier ones without a bolt hold open and other things to remember what they do. They make gadgets that attach to the charging ears to make it easier to pull the bolt back.