Since all BooKoo and variations are for larger portafilters, I still haven't printed a tamper station but I was thinking to remixing your design and the tray.
After a quick check I say 0.87 scale should be done and the tamping station and this model will work for 51mm. The maximum diameter of the portafilter (with ears) should not be larger than 72.2mm, with ears it should be smaller than 63.7