I will try the "save to disk" option, but meanwhile I was able to rename the files using Flexible Renamer v8.0 (
http://hp.vector.co.jp/authors/VA014...lish/FlexRena/). This utility accepts regular expressions, which can be tricky to figure out, but are quite powerful.
I used this search expression,
(.+)\s-\s(.+)\.epub
and this replace expression,
\2 - \1.epub
The seach expression tags the filename string preceding " - " as \1, and the string between " - " and ".epub" as \2. The replacement expression just reverses the order.