There are two UIs that people commonly use for p1999. Pretty much none of the eq interface mods work here because of versioning issues. You would need to modify the files extensively to get them to work with p1999.
https://www.project1999.com/forums/s...d.php?t=175946
https://www.project1999.com/forums/s...ad.php?t=28335
That's if you're going to play on Blue. If you're playing on Green forget about any interface shenanigans, you will play the interface you get with no mods.