You're correct that it's not that complicated of a machining job, but it is very important that they're done right. When we machine them, we pop the 5x5 pattern and hit them with a ream, then interpolate the center bore and the chamfers on all of the new holes. Every rotor should be dialed in based on the original center bore for a true center because the 5 x 4.75" hole patterns are not very true in our experience.
On the rears, depending on the rotors you choose to use, in addition to the 5x5 pattern and center bore, you will probably need to open up the hat area where the axle flange seats and possibly cut down the OD of the intergral rotor brake drum if you're using your OE parking brake backing plate (like with Bill Harper's kit). The C6 rotors are finish machined, the C5 rotors are not in this area and may interfere with the lip on the backing plate.
As for machine shops in your area, you might try the automotive machine shops first since you're more likely to find fellow car enthusiasts and possibly get a better deal that way. If they won't do it for you, they may know someone who will. Up here, the going rate for machine work is $50-$75 per hour, give or take.
Good luck,
Tobin
KORE3
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