I did this same swap to my 82 GT with a lot of time invested in researching the differences not only between Fox and SN95 parts but also early Fox vs. late Fox.
I started out building the car with Fox length
control arms, SN95 spindles, Cobra rotors / calipers, and 2000 Cobra R Bilstein struts. Goes together fine except you won't be able to achieve much more that - 1.5 deg camber. This is because the older Fox k-members are ½" per side narrower for a total of 1" narrower track width vs the later model Fox. I believe the change happened in 87? I'd have to dig out my notes.
Next phase of the build was to add the mysterious 87-88 Turbo T-Bird arms said to be ¾" longer to add additional neg camber adjustability. Thought this would be the hot ticket, not. Laying a set of T-Bird arms next to SN95 arms they come out to be the same length. Many people also believe the SN95 arms to be ¾" longer than the Fox arms, wrong again. If true, we should be able to put the SN95, or T-Bird arms, on our cars with 1/2" per side further inboard lower control arm mounting holes and only gain ¼ " per side in track width over a stock late model Fox. The SN95 arms are actually 1.33" longer than the Fox parts. This creates major fender clearance issues and more neg camber than desired.
So.....what I did was to find another k-member and move the control arm mounting holes inboard to allow for SN95 arms. ½" for old fox k-members, 1" for newer fox k-members, net gain in track width = .33" per side compared to a late model Fox. Much more manageable from a clearance and camber adjustment standpoint.
While I was at it, I moved the mounting holes up .80" to improve camber gain and roll center height. I believe I now have ¾ degrees of neg camber gain through compressive travel, would have to check the notes again for exact numbers.
Hope this helps....