ok, pull up a chair...this may take a while... JK
I'll rub through the basics for you on this one. Honestly, it would require enough modifications to warrant just scratch building a new one to really get it right. Here we go just the same.
First, the overall fuselage is too narrow, should be more robust. This would be a major change so I guess leave this one out. The nose of the model is shaped wrong. if you look at screen grabs or photos I've posted on my build you can see how far off it truly is. The facets of the nose were called "chisel nose" and the overall contours of the plane's nose and main fuselage are the primary design from Greg Jien's original concept.
The main fuselage could be made to look better by rounding the "square-ish look this kit has over the top. The only area that is this shape is just behind the canopy avionics hump for lack of a better word. The cockpit is too far forward, however if you add an extension to the nose this can be remedied. The nose isn't broad enough, nor does it have the correct angles and curves on the bottom section. Two things would be good to modify here. The area just behind the canards on the bottom side when viewed from the side takes a sweeping arc toward the nose of the plane. It stops where the facets start. All replicas of this plane I've seen to date have this area beveled / chamfered almost to a halfway mark along the fuselage to help meet the angular face of the belly intakes, this is not right at all. Also, a strong point always missed., making this plane more difficult to model is the fact that the entire bottom of the nose takes a downward sweep from the canards to the tip. The main turbine fan intakes side profile have a delicate curve to them when viewed from this angle. This again would be quite a modification to make but it's up to you as to how far you want to go on fixing this. The intake shrouds are way too pronounced stretching too far forward where they meet the area of the intake inlet "tunnel" as I call it. The rear engine nozzle cowling/shroud should be longer and more angled and not attached to itself as the kit represents. the cowlings for the engine nozzles are thicker with some "vanes" in the inner vertical curved wall. The drag chute/ drone area is too thin on the kit and needs to be made more contoured/ robust and rounded except for the ends. Nozzles are overly simplified, but for this model, get the job done, even provided with the inner burner cans, good deal.. Wing tips are surprisingly not bad at all, even possessing the curved tips. I'd say stick with the simplified recessed panel arrangement unless you have about 60 years to redo. The Firefox miniatures have one of the most intensive recessed panel line patterns I've ever seen on an aircraft. well this should get you going anyway, good luck and ask questions if you need to.
Sincerely,
Will