They installed a front and rear spoiler, fixed my drivers seat, fixed the bushings on my console shifter. That's all they did for me. Nothing mechanical. They were all very nice and seemed fair in pricing.

I dont have any idea about the skill they have for rust/body work and paint, but I saw a few cars they had personally and from that it looked like great work.
Its tough to give recommendations on any shop, Id say be sure anything you do get in writing, understand exactly what you will pay and be sure to understand what your expected results will be.
I can say if your Mach has original paint on the car that you will need to remove all that paint if you go with a Base Coat clear coat. That can add a few thousand to the job.
Quotes on mine have been between 6000-8500 and I have no rust.