I don't have an IC-2000H to test on, but I do have an Icom F-320S, and back when I had both, I seem to remember they used the same size. Seems like most radios use this size:
5 Pcs M4x8mm Zinc Plated Step Hand Screw Flat Knurled Head Thumb Screws Bolts
These work well on mobile brackets where you have restricted access with a screw driver.