I always want a dust cover, removable while playing, you could have a custom one made. Successful repositioning, where does it go during play?
Technics adjustable tonearm base is terrific, it can expand to 2 or 3 arms, so don't make the dust cover too small. I just installed that base for a friend on his SP-15. Impressive.
Technics removable headshell to make single arm more versatile.
Others more impressive looking, first impression, don't know anything else about either.