Hi.  You should be able to use an ordinary stereo phono cartridge on
the Edison disks, as the stereo records used a 45/45 recording system
which gave side to side for one channel and up and down for the other
channel.  Connect both outputs in parallel and enjoy the music.

Oh, by the way use the 78-rpm needle.  Radio Shack can order a ceramic
cartridge for you, which will work on any line level input on an amp.
There is a minor problem with RIAA equalization, but not worth worrying
about.  I have done this in the past, so I know it works.

Best to you.
Jim Cook