I mean why rely on a light aircraft to fill in the gaps based on a doctrine which allows the enemy to get in close in the first place? It would be far better to have a heavy interceptor which is a missile truck bearing a whole array of short, medium and long-range missiles and an added 20 mm autocannon if it comes to in-close fighting.
In other words, a swift interception and engagement with BVR and then they swoop in on the enemy and engage them with Fox-1s and Fox-2s one after the other, forcing them to exhaust themselves or break off and flee.
Unless of course you want a shootdown where the enemy aircraft falls into Iranian territory and so does the pilot which frankly would be quite nice.
that interceptor probably need 40000$ per hour of flight and light aircraft need 5000-6000$ per hour of light .
you can build that light aircraft for as cheap as 1/3rd of the price of that interceptor. and that interceptor even don't carry much more ammunition .
and the radar is not even that much stronger.
now you decide you want to send one interceptor that can use after burner and reach enemy at 2500km/h but ran out of fuel . or send three light/medium multirole fighter that can data link with each other and have better battle situation awareness and combined carry 2-3 time more weapon .and their maintenance is a lot cheaper and easier
let see the case for example F-15 and JAS-39
speed :
F-15 : can't supercrise but can reach up to 3000km/h but then the engine will need hours of hours and thousands of Dollar maintenance otherwise 2650km/h
JAS-39: can supercruise at 1.22mach , max speed 2450km/h and too reach that the engine won't toast itself
engine :
F15: 2 × Pratt & Whitney F100-PW-220 afterburning turbofans, 14,590 lbf (64.9 kN) thrust each dry, 23,770 lbf (105.7 kN) with afterburner
Jas-39: 1 × General Electric RM16 (F414-GE-39E) afterburning turbofan engine, 61.83 kN (13,900 lbf) thrust dry, 98 kN (22,000 lbf) with afterburner
weapon load
F-15: 10t on 9 hardpoint plus 1 gun
JAS-39: 7.2t on 10 hardpoint and one gun
combat range
F-15:1900km
JAS-39: 1500km
sevice ceiling
F-15: 20km
JAS-39: 16km
g-limit
F-15: +9
JAS-39: +9 -3
weapon
F-15: 8x AIM-120
JAS-39: 7x Meteor + 2x IRIS-T or 2x AIM-9x
RADAR
F-15: AN/APG-63(V1-V3) depend on the model
JAS-39: Selex ES-05 Raven AESA radar
its up to you to decide which one is better 1x F-15 or 2-3 x Jas-39 for your scenario