Get a 12" with a removable head-shell so you can easily swap cartridges. I'm not sure it matters which arm hosts the mono. Try both and report back. I have 12" and 9" arms on my main table.
Mono record sounds like stereo
So I have been playing stereo records for 40 years. I’ve recently acquired some Verve Japanese reissues. Listening to Metronome All stars tonight and there is clearly separation. I hear horns predominantly on the left and xylophone and drums on the right. This is on an Ortofon SPU synergy stereo cartridge. Is this normal ? I’m sorry. I’m new to Mono. I bought about 50 verve and Blue notes last week and got some monos on accident. My system is balanced and the room has extensive treatment so I’m lost !