Thanks! I can't upgrade this application to 5.x yet, so your suggestions were helpful.
I had missed the Type Converters page in the settings. Also I missed the "Automap Unmapped Entities" command, which was the main thing I needed to save me a lot of time
I tried your settings and auto-map still didn't set the type converter on the new mappings, but it at least created the database columns and mappings for these fields, which was more than it was doing before.
I had to write a program to check over the project file and make sure the table and column names were the same for both database engines, so I had that program set the type converters for me, too.