I use regular diamond styli with good results.
The reason for the use of fibre and cactus needles was because the aluminum is a soft material and would be easily damaged by the sharp steel needles of the day. The bare aluminum discs were (and are) even more prone to damage by styli than the soft lacquer coated discs (commonly, though erroneously, called acetates in some circles). Modern cartridges aren't made for use with the straight fibre and cactus needles that would have been used in either heavy acoustic reproducers or the slightly lighter tone arms of the early amplified turntable mechanisms which used crystal and rochelle salt thumb screw cartridges.
I would refer you to three early media transfer experts in your general locale (within a few hundred miles) who would be of great benefit to you. All are members of the Association for Recorded Sound Collections and I'm sure any of them would be glad to consult with you on this subject.
Seth B. Winner
Center for Popular Music
Middle Tennessee State University
From: Association for Recorded Sound Discussion List <[log in to unmask]> on behalf of Paul T. Jackson <[log in to unmask]>
Sent: Thursday, April 25, 2019 8:05 PM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Aluminum transcription disc fiber stylus
A search on Google for "fiber needles for recordings" will bring up a
number of vendors. There's also a machine for making them. Some use cactus
Paul T. Jackson
Steilacoom, WA 98338
[log in to unmask]
On Thu, Apr 25, 2019, 2:05 PM Warner, Douglas <[log in to unmask]
> We will be transferring some aluminum transcription discs. We understand
> that fiber needles are optimal. Does anyone have any leads on acquiring
> fiber styli?
> Doug Warner
> Vice President, Technology | The Paley Center for Media
> 25 West 52 Street, New York, NY 10019 | paleycenter.org
> [log in to unmask]<mailto:[log in to unmask]> | T 212.621.6665