We tested the CPP spindles on Mary's car for a few events. The spindles were fine, the GMR hubs had some play and adjustment issues so we had to stop using them.
I would take the following into consideration and look at costs.
The stock spindle is OK, nothing really wrong with it, but to put larger brakes on it you have to cut the old caliper brackets off and bolt in an adapter bracket. The best stock spindles are the late second gen with larger outer wheel bearing. If you are using a floating caliper, the stock spindles work well and a taller upper ball joint can be used to help the poor camber gain. You need a hub to mount the rotor on since all second gen's came with disc only.
If you go to 13" or 14" rotors, along with non-floating calipers, then pad knock back is going to be an issue. How big an issue depends on a couple of other things:
If you have power brakes, the pedal moves half as much as manual brakes, this reduces pedal drop by half, so pad knock back is perhaps tolerable with power brakes, and terrible on a manual system. It also matters if the front and rear are non-floating calipers or just the front, and what size master cyl bore you are using.
The Corvette unit bearing hub fixes the knock back problem (in front). Using it on the CPP spindle allows everything to bolt up. The CPP spindle does not have a turn stop on it to limit turn angle, but neither do other aftermarket spindles.
You would have to use a tall ball joint to see any geometry improvement.
ATS makes a nice spindle that is forged Aluminum with 1" drop plus it's taller to fix camber gain.
http://www.speedtechperformance.com/...rod/prd279.htm
If you are on a tight budget, then look at floating calipers using corvette rotors on a stock spindle, then add a tall upper ball joint.
The CPP is middle ground and needed if you go with manual brakes and/or 6 piston fixed calipers.
The ATS spindle is top of the heap so to speak.