This should be the end state for this project.
Got the proper MI optic mount, and the color-match buttstock.
Next step is going to be to lay in more (at least four, for six total) BX-25 magazines. They are functioning perfectly, but are a significant PITA to load. The PITA factor goes way down if you are inside your warm house with good light and a nice height workbench and a cold beer or hot coffee nearby.