A modified JH-7 Would work as EW growler role
Since it has ability to outrun other planes due to it's Top Speed
The plane is also quite large that it can fit in many sensors
Would imagine this bird can stay up in air longer as well
The Thunder platform would be better to escort the unit , and be armed with weapons
Chinese have opted to convert one of their J-16D platform to EW role , so we may not even need to convert anything , Just get 1 squadron of J-16-D
The size of JF17 would be limiting factor as JF17-Thunder is in true sense is a Fighter Jet not designed to carry bulky EW gadget , it can do that role but loitering time in air would be less I would assume
May be if J16-D stays in air 3 hours (speculation), JF17 would perhaps would need to refuel in 2.3 hours (speculation)
But it is in theory possible to convert JF17 Block 2 , into JF17 Block 2 (EW) mode
Since we already have 50+ Block 2 , we will have flexibility to rotate the Growler mode if need be