You are fortunate in that you already have all your mail on the same mac and do not need to deal with a device-to-device data transfer. Last time I checked, Outlook 2016 for Mac meets all 'Official Guidelines' in he industry, hence is compliant with them.
I will be honest upfront, without paid software this will be next to impossible to achieve, I therefore recommend that you stay with Outlook 2016 for Mac and save yourself the trouble and expense.
