landing gears should be redesigned and because the F-5 fuseleg has low width it will be very difficult to do that but if the wings are belong to wider planform with two 1 meter diameter engine , it will be possible and the fighter go to semi-heavy fighter jet.
http://www.spacedaily.com/reports/China_Eyes_J-10A_Sale_To_Iran_999.html
Other project has named Azarakhsh with 8 ton as empty weight and old Azarakhsh project which was based on f-5 renamed to kowsar.
Exact analysis of j79,f4,Al21f,... seem you are an expert in mechanical or aerospace.
Best job is to scale up j85 external diameter to 120 centimeter and adding low bypass to make heavy turbofan.
J85 has good setup as you see the f22 and f35 engine have nearer setup to j85.
Twin spool scaled up...
Kowsar has cruize speed less than 1000km/hr but it is a supersonic fighter jets and can be used as a point defence fighter .
It's radar can not detect f22 or f35 but can detect f15 and f16 and it is enough but iran need to design some device and strategy against f22 and f35 also.
My be kulchoga...