SysVita OLM to PST Converter Tool if you're still looking for a way to convert OST files to Outlook PST on a Windows or Mac computer. The software can convert OLM files and save them to PST as well as a number of other file types like MSG, MBOX, EML, EMLX, PDF, HTML, etc.

A quick option to export OST data to PST file format is to use SysVita Exchange OST Recovery Software. Contacts, attachments, and other stuff are all imported from the OST file to the PST file format.