The black sight was hard for me to see too. I have put paint, either yellow or orange on some of my firearms that I couldn't get a fiber optic sight for.
For my MK IV .22/45, I ordered the Hi-Viz fiber optic front sight and shallow V-notch rear from ShopRuger.com.
The front sight comes with extra F/O tubes in red and green and a tool to help change them out. The V-Notch rear has a white stripe pointing up to the deepest part of the V.
It's very easy to set the green tube on the top of the white stripe and fire away.