Here are some closeups of the gate/pump mount:
I wonder what that small portal on the top is for?
This looks like a conflat on the side you can’t see:
You can see a ring where the rubber gasket from the pump would go:
But how do I attach the pump? Where do the screws go?
Prometheus Fusion Perfection 
no clue, but much luv for the vacuum chamber!
I don’t think that turbo is supposed to go horizontal and so I don’t think you should be trying to mount it that way. It looks to me like you will need an elbow flange to connect your upright turbo and the gate valve. That will be one big elbow…
Is that portal the gas inlet for actuating the valve?
UPDATE: this gate interface was not originally used to connect the pump…
it was used for this mechanism that inserted and removed compact disks.
UPDATE: the whole top half of the chamber separates, using the same gasket as the lid to the top.