Selection of mono phono cartridge.

Within the last 2 years I upgraded my system with a new turntable (Teres 340), arm (Graham 2.2), cartridge (Shelter 901) and phono amp (Manley Steelhead), which has left my previous set-up (VPI MKIV, SME 309, Grado Ref) essentially unused.

I have recently acquired over two hundred RCA/Mercury mono classical LPs. I have seriously considered upgrading to a high-end turntable with two arm capability, I wonder if I should try a mono cartridge in my VPI first.

Would a mono cartridge in the VPI set-up likely sound better than listening to the same records with the stereo Teres set-up? If so, which cartridge might be an appropriate match for the SME-309? I noticed that Shelter, Lyra, Benz, and Grado all make mono phono cartridges.

Thank you for considering this question.