It is my understanding and experiance that the relocating of the upper control arm aids in keeping the tire contact patch flatter when going into turns. The control arm relocation also lowers the car about an inch or so, lowering the center of gravity, again improving handling. You should lower the rear as well to keep everything working together. To really tighten things up, front and rear sway bars are a must, as well as some gas shocks, like KYB's. 16 inch wheels are good, 17's are better, and anything larger than that will affect ride quality due to the reduced side wall of the tire...I have 17's on my car and it rides nice.
I went a little extreem as far as lowering my 69 convertible but I will say it handles like it is on rails, and the ride is pretty damn good for a 40 year old flexible flyer.
Mustangs Plus in California have suspension upgrade kits that could give you everything you're looking for.
Hope this helped
Joe