Iran needs interceptors/air superiority fighter to protect air defenses from over saturation attacks from fighter jets and defend key areas.
Iran’s F-14’s single handly protected Iran during the Imposed War.
Thus you need something in AL-21/31 class ideally. A fast and powerful engine to allow interceptor to reach any point inside Iran quickly with a 300KM+ radar and 100-200KM air to air missile to keep enemies on their toes. A heavy fighter that can stay in the air a good amount with a large combat radius.
J-85 is worthless for anything outside of light fighter class. j-79 is not ideal for future iterations.
If Iran is going to build its own fighter jet it makes sense to plug in the most pressing need, which is an replacement for F-14. Iran has about 15 years to do that domestically before F-14’s will likely have to be mothballed or retired completely. After that, the skies of Iran will be pretty defenseless outside of a some aging MIGs