The firewall side of the splash panel is matte black. The side above the tire has black matte also. The splash panels or fender wells, if you prefer, were installed after the body was painted but they were frequently over sprayed with body color as the result of a later repaint, usually as a result of body damage in service. Rear wheel houses were painted body color. Note that many restored examples exist with body color on the fender wells, so I suspect that this may be an area where the treatment varied from plant to plant. I would repaint what ever color is on the base coat as that is probably factory. Yours appear to have been matte black.
Dave