We did nearly the same thing on HP c7000 blade enclosures. We could afford some downtime, so we just exported an .ova to shared storage, and then imported it into the new VM cluster. That worked really well. I would advise testing and timing the moves, so you have an idea of how long it will take.
We had multiple hosts built out in the new cluster, but the actual virtual server move would be essentially the same.
@jonathanlackman