Sounds like plenty to me, esp. with high efficency Lowthers. I've got about 78 db total gain from my pre and it can handle a Benz Glider L2 (o.25 mv) just fine, driving 89 dB/watt/meter Vandy 3Asigs.
My Jadis JP80MC had those specs for phono, and I think 20db gain in the line stage, and had no problems with a cartridge with a lower (.3mV) output than yours. Should be fine based on those numbers.
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