No, you cannot use the new handle with the old connecting rod/primer tray.
The new XR uses the same body, but the connecting rod end is larger and the handle's leverage angle is different. If you use the new handle with the old connecting rod/primer tray, the old connecting rod end will be loose in the new handle and you'll only be able to move less than 1" of handle travel, not enough to apply enough leverage/force to seat a primer.
To use the new handle, you must replace the connecting rod and the primer tray - effectively, a new XR. Only part that's interchangeable between the old Auto Prime and the new Auto Prime XR is the body.