Inch and a half filler scribes to match the cabinet, custom made top to fit the space. Any thing less is just making stuff up to cover a gap. Nothing wrong with making up stuff to cover a gap if your OK with that. I make and install cabinets for a living and what I described is what I would consider doing the job correctly and it is how I would do it at my house. If you are in the Portland Oregon area maybe I could help you out. Offer void if you are a serial killer.