If you want to convert MBOX files to PST. I would suggest you, according to my personal knowledge, Use the professional tool DRS MBOX File Converter. The tool is capable of converting multiple MBOX mailboxes to PST Outlook and converts other formats such as EML, EMLX, MSG, and HTML. It supports all Windows OS. You can download its free trial version and migrate and convert the first 50 items per folder. You can easily work with DRS MBOX to PST Converter and other more tools.