Hi Mike,
Had another thought (RIGHT after I hit "Post reply" of course!) ... cut coves in thin strips of matching material, cut square slots in cabinet and glue the cove "trim" into the slots as needed. This will allow you to experiment with different radii and gap settings if you choose. This is probably much safer than plunge-cutting large slots on big panels, and much more tolerant to bad cuts.
As an added benefit, if you are making the Leslie cabinets from materials other than solid wood, the cove trim does a wonderful job covering the edge grain ... allowing you to experiment with different cabinet materials as well.
Hope this helps.
Regards,
Rick