Hi Cameron,
The 460EXM is a popular camera and uses the Sony EXview CCD which is very low noise and has an excellent spec. The pixel size is important and at 4.5um will be well matched to the 130PDS which I believe has a focal length of about 650mm. I wouldn’t get too hung up about a high QE, providing the camera has low noise then you just expose a bit longer if you’ve got a slightly lower QE camera.
Best of luck finding a second hand one. Before you purchase get the seller to send you an uncalibrated light image and a dark and check for any major CCD chip blemishes or dead pixel columns. Use your existing camera as a guide to what you find acceptable.
Peter