Splitting a GitLab installation into two

We have a GitLab 7.x (don’t know the exact version) self-hosted installation (CE) with over a hundred projects. Half of the company has been acquired and we need to split the installation into two with different projects belonging to different companies. We would like to keep all repositories, issues, MRs, and other misc data associated with each project.

I believe that the best course of action is to do either of these:

*Create a new installation with the exact same version of code and use the rake backup/restore tasks to clone the state into the second installation, then just remove projects/groups/users as needed from each installation
*Upgrade from 7.x up to at least 8.9 to allow project export, expect the needed projects, and then import into a new fresh installation

I believe that either one of these will work, but is there perhaps another way I might be unfamiliar with or any caveats associated with this process?