Didn't think the cone synchro as much good in a mini at any mileage. Might have been OK in an A35, but drivers tended to be a bit more enthusiastic in a mini.
A couple of years ago I picked up a baulk ring conversion kit from ebay. I'm shortly going to be attempting to fit it to my recently acquired gearbox. Hopefully I can source the bearings and other parts that are needed.
i have a mk1 ,1960,that was fitted with the kit to a cone box a few yr AGO and seems very good
shame they dont run as quiet afterwards
must be mismatch of gears old against new,,,,