Do you know what covering was used to cover the model?, plastic film, or fabric?"... solatex and 21st century are both fabrics, although the 21 century has less texture to it than solartex... plastic films, you have monokote, ultracote, plus several other off brands.... the monokote "lusterkote" paint will match monokote colors, but will not exactly match other plastic films or fabrics like ultracote, solartex, 21 century, etc... its a PITA to get any paint with a good color match to any iron covering, unless you get it custom mixed... or if you plan on painting the entire model, most will cover with natural solartex, and then spray paint their colors over the natural solatex, so color matching doesn't become an issue.
If you don't know what the model is covered with, you can try taking a wing panel down to your LHS and see what coverings they have, and try to match it up, or see if they can aid you if figuring out what type of covering you need to make your repairs with.
John M,