I’ve shared some set up help in another thread, which you may want to read. The lenses in use are the Schneider Kreuznach Macro Symmar 120 and Rodenstock 75mm 2X f/4.5. This thread also includes a full set of other equipment you’ll need to make this all work. Just skip the parts you already have.
Hope this helps!
Setup + Lenses + Equipment
Further thoughts on the SK Macro Symmar 120 here:
EDIT:
Stay away from dedicated scanner lenses, such as the Nikon Coolscan lenses or Minolta DiMage lenses. While these are awesome pieces of glass, they are a PITA to work with due to their wide aperture of f/2.8 (Coolscan).