A few names come to mind.
Leigh McKinney from Eclipse (even though his current workload of Eclipse trumpet orders might make his time frame a little slow for your tastes)... he totally restored my Olds Opera Cornet with Nickel bell and it's better than new. Truly world class work.
www.eclipsetrumpets.com
Jim Becker from Osmun Music is my favorite technician and a true master craftsman. He's worked on all my horns and the only guy I'll go to in the US.
www.osmun.com
Charlie Melk has received rave reviews, and Rich Ita does a great job as well.
Best,
T