The Focusing Screen Adapter 41025 was replaced in 1992 with an improved version 41050 which had the Acute-Matte screen. This is the version you need, which was again replaced in 1997 with the last version (41057) which had a built-in bubble level (all this information is from Nordin, p230-231).
You might be able to replace the screen in a 41025 with an Acute-Matte, but considering the cost of these things now and how easy it would be to mess it up, you would just be better off finding the later version and selling the one you have.
John