I've had a bit of experience in upgrading Springfield Armory guns and you should know that there could be trouble in your future.
The Springfields are very well-made 1911's, and thousands of people swear by them (I have one myself), but they are not necessarily built to USGI dimensional specs. In fact, the hammer-sear-safety area is one of the most problematic. I have had numerous instances of Chip McCormick hammers in Springfield guns dragging on the sear when the trigger is pulled. Also, you often can't get the safety to re-install on a McCormick sear without grinding either the safety, the sear, or both. Nothing is wrong with the McCormick parts; they're designed for USGI specs, which the Springfields frequently do not match.
Another issue is that if your Springfield comes with a spur hammer you will have to replace or modify the stock grip safety if you use a McCormick hammer. The McCormick hammer is a Commander pattern and the stock grip safety will be too tall to allow the slide to retract over the hammer.
Again, this is not a bashing of the Springfield. They are fabulous guns as-is. They are just not as conducive to custom parts installation as, say, a Rock Island is.
I think you will be much happier if you just buy a little better grade of Springfield to begin with and basically let it be. Most of these will come with a beavertail grip safety, and have trigger pulls in 4-5.5 lb range, which is great for all but the most serious target work. The Wilson mag is a good idea and will work in the Springfield just fine. You won't need the 18.5 lb spring though, unless you plan to put a lot of +P ammo through the gun. Otherwise, the 18.5's can cause the muzzle to dip when the slide returns, decreasing rapid-fire accuracy. A 17 lb Wilson spring is a good compromise if you want a little more oomph than the stock 16-pounder. The price is about the same as a Wolff.
-Zims
