GSh30

Hey everybody, I've been playing SF2 for a few years now, and I've been dabbling in custom modding lately. What I've been trying to do is essentially make an upgraded MiG-21, with a more powerful engine, NATO weapons pylons, and a different radar system. I didn't think any of this required new assets, just copying over a MiG-21 to a new folder and editing the INIs to what I'd need them to be. I'm not sure what I've done wrong, but my new aircraft isn't showing up. I figured I'd come to a group of people who know way more than I do in this realm, so any help would be great.