I managed to install and run 0.8 with "redis": "version": "0.12.1", and connect-redis v2.0.0.
So use those versions of node and npm and you should be fine.
Pay attention if you use nvm and different users to run the blog! Check the npm and node version with the user that starts the app.

I'm in exactly the same situation, upgrading 0.7.3 nodebb with redis version.
I cannot find documentation for older version.

I managed to install the packages using node 0.10.48 and npm 2.15.1

But redis and connect-redis are not included in package.json and the new versions that I installed manually don;t work.

Can someone tell me what versions were used in 0.7/0.8 versions?