Since you mention the old conteoller is 8.3, it should be clustered ontap.
in that case.. rather than building a new cluster with the new hardware.. why dont you upgrade the existing controller to ontap 9.1
and use the new hardware to join to the existing cluster and use the volume move
to migrate data from old controller to new controller.
If you take care of the ISCSI LIFs from new controller and mulipathing for lun.. the volume move should be non-disruptive.
Or you can use the ARL non-disruptive headswap.. if you haven't done this before.. i'll recommend you get some help to do this procedure.