yet another CV joint thread, I think I know what I did wrong. Options

[blabla914]

Here's the story. My CV joints are trash after 60k miles.

I put 4 "new" CV joints in my 914 7 years and 63k miles ago. I purchased the joints from transform and they are 914-4 joints with the 4 bolts and the large holes for the pins, not VW parts. I say "new" because they could potentially be rebuilt. I don't know for sure.
Until 2004 my car had a carbed 1911 type 4 motor, 7" cookie cutter wheels with 205-50-15 R compound tires (Yokohamas, then Khumos and Michelins for the street), and -4 CV joints with the otto stubs to run 911 hubs. As of the beginning of 04 my car now has a rebuilt 2.0L E motor with weber carbs, but I've only put like 5k on the car with the six. In the past 5 years I have autocrossed the car quite a lot and run it on the track once at Watkins Glen.
These CV's have always been packed with Red Line CV-2. My repack interval has been about every 25k on the clock which is actually every 20k when you factor in the fact that I run 22" dia tires opposed to the stock 25" dia. When I last repacked them they showed signs of wear, but nothing to get really excited about.
When I started hearing what sounded a lot like a flat spot on a tire, but then disappeared when I put the clutch in I pulled the axles and found the CV joints to be trashed. I mean multiple, large divots in the outer races and lots of evidence of the cage rubbing on the outer race.
Here are my contenders for what I did wrong:
1. Wrong grease. I thought Redline CV-2 was up to the application. Anybody else using it? What is your experience?
2. Too long between re-packings. When I dismanteled there was plenty of grease in there and it still had a nice red/pink color. It's thick and feels good to the touch, but maybe this doesn't mean squat. I think re-packing every winter sounds like a good idea.
3. Expecting too much from the -4 CV joint. Honestly, I did not think that a 2.0L six or a 1911 four would put that much strain on these joints. I do all my own work, on my own time, so I'm not the 4000rpm and drop the clutch type. I drive my car pretty hard, especially on the autocross course, but I don't think I abuse it off the line.
Now that -4 CV joints are NLA my choices seem to be used joints, finding someone to rebuild them ( I doubt mine are rebuildable), or some kind of swap. Looking for your recommendations to withstand the six and R compound 225-45-15's on 8" rims and 8-10k street/autocross/track miles per year.

Thanks,

Kelly