Deploying Projects from 5.9.x REPO to 6.X REPO

Please advise me on the steps to take a fully configured/tested project from a 5.9.X REPO where it was developed to DEPLOY it to a 6.0.X REPO.
( I have 2 ETL servers, 1 Development 5.9.4.7 and 1 PROD version 6.0.1 scenario ( i actually have 5.9.4.7 PROD ETL servers too)
1. I don't want to upgrade the 5.9.X repo. yet hence no in place upgrade of the development ETL cuz i will not be able to do work for the 5.9.4.7 PROD servers)
1a. I tried synchronize repo. between the old and new databases, it didnt work
1b. I tried backup and restore the project zip file between the versions - it didnt work
1c. I didnt try to export the project object by object , and import and reconfigure them it cuz it seem to be a lot of work.

The key here is :
When you make a backup using version 5.9.4.7 do you get one file inside or several?

in the zip file is a single .dat file.

I am a little bit confused about what you are trying to achieve.

Are you saying that within 5.9.X repository you have multiple projects and you want to copy just one to 6xxxx repository?

Yes, Exactly, that, how can i get a single project from a 5.9.X REPO to a 6.X repo?

Run version 6.
Run repository synchronization wizard and use repository backup as source.