On the smaller system I picked up a 1000l/s Pfeiffer turbo to put on it as well. It had a bad bearing and I picked up another one and installed it. Oil was a pain to come across, very specific for the pump, a fomblin.
The biggest issue was mounting it to the machine. The old pump was mounted to the cold trap with a 6" ASA flange. I was hoping to remove the cold trap and connect directly to the isolation valve but it turns out that the cold trap is what supports the whole system. I got a 6" ASA flange and a 10" Conflat flange from a friend and welded them together to make an adapter. I used a reusable rubber conflat seal instead of the single use copper ones and it looks like that was a mistake, sprayed down the joints with IPA and found that the rubber seal is leaking. A copper gasket is on the way.
I have been waiting to finish the control for the other system to run the roughing pump and blower, they are shared between the two systems.