Only two places id use and recommend are Westend performance and duncan & foster.
Sam at westend is responciple for some of the best Drag engines around and many of the top fuelers as well, his done all of my machining for the last 9 years and ive never once had a problem with his work. His all to familiar with the Rb engine as well,
Duncan and foster we use for all out machining at work, they do good work and turn around is very reasonable time wise.