Just a quick update. The ring did eventually connect up but required me to unplug the DAC cables and plug them back in - then the ring topology formed instead of the chain.
Also, I was mistaken on the VSF port links. They do not need to be linked to the same port on the other switch as this is impossible to do on a 3 switch ring topology. For example, Link 1 on the top switch is plugged into Link 2 on the bottom switch.