Ian, personally I wouldn't recommend raising the maximum pressure beyond the preset pressure on these compressors, as they'll struggle to reach a higher pressure. They often struggle to reach the set maximum pressure, let alone anything higher!

By the looks of it, that MDR kit you link to, combined with the differential kit should do the job nicely for Suesi.
Set it for 7bar cut-in, and you should be able to set the cut-out for not much more, that way the compressor isn't having to reach too high a pressure before cutting out. You probably don't want the cut-in pressure too near the cut-out pressure though, otherwise the compressor will be continually starting/stopping.