What you found is correct. After installation, the top cover plastics and metal shielding of the Quadra 800 obscures the eject button of the CD-ROM drive. The front bezel for the CD will not mount on the front of the top cover for the same reason.
However, there are two versions of the cover top, service p/n 922-0847 for the Quadra 800. The one that causes the fit problem has engineering p/n 805-0456-08 and the one that fits correctly has engineering p/n 805-0666A. This information will be forwarded to the organizations that can make changes in the Finished Goods kits.
In the meantime, for the customers the only solution is to order p/n 922-0847 from the service price pages.
The correct audio cable is available as a service part. The part number is 922-0842.