I had to waste invest more time than expected to reverse engineer some differences between the "as built" wiring terminations vs. the drawings but was able to figure it out eventually.  Next week, we'll use the existing iLIGO pump system as standby during the vent.  Once the vent is completed, we will then remove the iLIGO Turbo Station and the iLIGO 10" isolation gate valve and install a new VAT gate valve and the -v1 Pfeiffer Turbo Station.  We will then pump back down using the hybrid setup consisting of the new Pfeiffer Turbo backed by the iLIGO Edwards QDP80 backing pump by using a custom control cable.  Once the recovery pump down is done and the pumps shut down, the iLIGO QDP80 will get replaced with a new HEPTA pump and then both newly installed pumps can be brought up to the current revision.  In a perfect world, this could happen ;)