I have used best machine for my builds. They have done a lot of hemi's in the horsepower range you are talking. It doesn't need to be an exotic combo. My 604 with CNC ported old style MP heads small cam pump gas made 860hp with a sheet metal crossram. I would give them a serious look.

Don't know much about FHO, people seem to like him, i have talked to him about parts before and he sold me an EFI intake for a customer car, seemed alike a nice guy. Barton has been around, but i don't know if that is shop you absolutely need to go to, its not like you were building a superstock class motor.