I think nano-composite could do the job and we are good at it or at least with little investment and efforts we could fill the gap...
F-35 Features Nanocomposite Structures
Without the ability to build a large single peace Titanium bulkhead Iran's ability to produce a viable fighter jet with sufficient thrust, range & payload capacity and will remain in doubt!
F-35 7085 bulkhead
F-15 Ti bulkhead before and after press
And once you develop the capability to make large Ti blocks and the tools like massive vacuumed ovens presses needed to build the bulkheads then Ti Wing tips and other Ti parts shouldn't be a problem
FYI building the F-35 wings also require massive vacuum ovens
And due to Sanctions NO one will EVER sell Iran massive Ti or high grade aluminum composite blocks at an affordable price due to sanctions so 1st of all to produce a viable fighter a Ti industry would be a requirement!
Iran could potentially make large Magnesium alloy blocks and cover them with Nano coating and layers of composites to build a bulkhead but we would still need large vacuumed oven presses to build the bulkheads
Also having an internal weapons bay will reduce the requirement on the wings payload capacity.
But none of these are a necessity for an R&D program to build your 1st working prototype!
For now the main problem Iran currently has is a lack of will to build a more capable fighter prototype!
And an absolute miscalculation as to what Iranian fighter program should look like and what type of fighter program Iran needs to put it's human resources towards building!
In the past 2 decades every fighter program Iran has put Human Resources towards has been a Light Close Air support fighter from the Shafaq(M-ATF), Azarakhsh, Simorgh, Saegheh,Q-313, Kowsar, Bavar, FB-44...…
And without exception all of them are CAS fighter that would be useless in a country the size of Iran with the security concerns Iran has!
And when every fighter program in the past 2 decades has been of a CAS fighter then clearly this is a leadership problem!
The French built the Mirage IV in 1960 which is a Mach 2.2 Platform with a combat radius of +1200km and ability to carry up to 16x 1000lb bombs with engines that were less powerful and less sophisticated than the J79's
So clearly this is NOT a matter of technology and if Iran wanted to and if they had spent a sufficient amount of time, human resources and money on it they could have easily built something far superior than the Mirage IV by now!
By the most part the F-4 Airframe is a poorly designed Airframe and using the J-79 engines Iran could easily build a superior Delta wing design that would be sufficient until Iran could come up with a turbofan replacement and in the future an Airframe that can handle higher G's....
The problem we have today is miscalculation made by our leadership!
A single Mirage IV could easily do the job of 8 F-5's against targets beyond +300km of Iranian soil so if 8 Iranian Kowsars end up costing us $132 Million USD ($16.5 Million per Aircraft) rather than building 8 of them you would be far better off building a larger Iranian supersonic fighter bomber about the size of the Mirage IV with Iranian upgraded version of the J-79 at a production cost of $132 Million USD per Aircraft.
This obsession with CAS fighters is a total miss calculation from Iran's leadership and it seems that they just can't comprehend that just because an Aircraft initial purchasing prices is cheaper and just because the aircraft's operation costs, maintenance cost and fuel cost by comparison is cheaper it doesn't necessarily mean the aircraft is cost effective!
And with force multipliers you can afford to spend more money per Aircraft on building better fortified bunkers, more money per aircraft on SAM & other defensive equipment, more money on ground decoys, more money on sensor and targeting equipment, you can easily have a larger portion of your fleet ready to scramble to protect them against incoming missiles, you can afford to put laser countermeasures on each aircraft and IRST and IR missiles to take out any threat that gets within visible range of your fighter you can deploy a larger number of longer range missiles to take out enemy SAM & runways to protect your aircraft and the list goes on an on!
