Frank,
Here are my suggestions:
The Repro GTA exhaust we have at Centerline is quite nice. I have it on my 2 Liter and the difference is quite noticeable. I think it will work best with the GTA headers, though. You have the option of a full exhaust or a side dump that is a bolt-on.
As for engine rebuilders for that kind of power, Rex Chalmers comes to mind. See some examples of his work at:
http://www.alfarex.com/. His Standard charge is $1,500 plus parts and machine work for a hi-po or race motor.
The $8,000 figure for George's motor is not unreasonable, though. The parts to build these motors add up fast.