really the only problem with the v6 stangs is that they are only 150 horsepower,can't remember the torque...but with the weight of the car,it makes it pretty slow...there are some aftermarket parts available for the 3.8...you could swap in steeper rear end gears,add a k&n,and a dual exhaust,to make it a little faster....but without adding a supercharger(which vortech does make)you won't even come close to competing with even a stock gt...
btw...my wife also prefers the 96-98 taillights,but loves her car so much that it is totally a non issue anymore...
but if you look hard enough you could even possibly find a 96 gt pretty cheap,i've seen them advertised for pretty decent prices....but good luck with whatever you decide to do...but take your time and shop wisely(we did)and you should be able to find just what your looking for(we did)...good luck...