I recommend you to run the Pre-Upgrade Readiness Assessment Tool (Assessment Tool). The tool generates a report detailing the precise impact on your environment and gives suggestions for replacement metrics when upgrading/migrating to vROps 8.0. You can use that information to export the existing customization and replace the ones that are discovered through the Assessment Tool.
Keep in mind that some customizations may not be exported and need to be re-created in the 8.0 environment. If you configure the vCenter adapter on the 8.0 environment be aware that this can increase the load on your vCenter to collect the data into vROps, due to 2 active vROps instances.
My v8 environment is from 6.x and did not enjoy the upgrade, got it working in the end. (bugs like no room for photon upgrade etc)
here's some information on manually backing up v7 content though :