There are some factors which help you to decide whether an OST to PST converter is reliable or not. According to my judgment if software has fast conversion process, short time consuming and result oriented then it would be more reliable. I would like to refer ATS OST to PST conversion software which perfectly matches the above criteria also it supports MS outlook 97, 98, 2000 and above versions.
Get more details: https://gallery.technet.microsoft.com/office/Exchange-OST-to-PST-12f7656a