When the Library of Congress archives acetate and shellac records they use diff cartridges with styli that correspond to the exact size of the groove as there were quite a few variations in cutting standards in the early days of recording. They also use Q-tips with purrified water to clean the record as it spins (I find this to be a great way to deep clean especialy dirty records). There was a special on either PBS or Discovery about this a few years ago. I'm not sure you would want to go to the same lengths they did but if you can find a copy of the special you might glean some useful info.
Good luck!
Good luck!