Hello Black Label,
Yes, we did the 3800 engine swap on my 93 Grand AM about 2 years ago. Jeff at Engineered Performance (
www.engineered.net) did the work. It runs strong and def. packs a punch!
As for the CAI .. I've seen just about every setup. What you are describing seems functional, but seems like it would be a hard install, especially with the custom fender mod. On my car now, I am not running a CAI setup.
I don't know much about Milzy Motorsports, however, I have heard the name. I would do a small order with any smaller company to see how things go. Build a relationship with them and if you are pleased, order more stuff.