If the Beatles box are your only mono records, I think you can get away with a stereo cart. I was playing Rubber Soul back and fourth with a mono cart and a stereo cart. The mono is definately better, but the stereo came pretty close. Older records cut on a mono lath...1950-early sixties sound like crap with a stereo cart. A dedicated mono cart is a must to enjoy those Columbia mono masterworks ML and CL series records. When I use a mono cart I do not use the mono button to sum the channels on my preamp. It kills the tonality as Synatx mentions, IMO.
