The Zoerk PSA for both Mamiya or Pentax 645, will fit your 1ds with no problem. The issue is when you shift, it's always best to shift the camera, not the lens. Thus you need an L bracket, to mount to the foot of the Zoerk PSA. Use the RRS generic bracket it will work fine.
I shift for resolution, not as much true pano's
In my work, I shift with the camera in the Portrait mode, across the frame. This will give you 3 portrait images, which you then combine for a high res landscape image. You can get this to work on the 1ds, with the RRS L bracket.
If you want to shift with the camera in the landscape position, up and down to create a portrait orientation image, you will need another adapter to allow this type of shifting as you can't mount the Zoerk on your tripod.
For true pano's, where you are going to shift the camera body in the landscape position, across the subject, you will need the same 2nd adapter I referred to above.
Net, it's not as easy as it sounds on the 1ds, but it works and can create some amazing final images.
Paul C