I noticed you also painted the inside of the housing blue. Their are very few illumination bulbs in these panels and those have blue tint difusers over them. The factory white paint served to reflect and spread the light. Some bezels have small areas painted flat black the prevent glare on lenses too. I dont know from experience that you wont be happy with your gauge lighting results but I do know the factory never wasted a drop of paint anywhere.
They had a reason for painting the insides white. Cheers