Teardown after spun bearing

[Vintage914Racer]

Long story short, I was at a track event last year and heard the ominous rod knock. I immediately pushed the car in the trailer and finally got around to the teardown. I was thinking the worst but it doesn't appear that bad.

The #4 and #6 rod bearings are shot, but it seems I shut things down early enough to prevent extensive damage. The rods still look good and it appears we can polish/machine the crank and reuse it. There were no signs of oil starvation or detonation, rather it looks like the bearings were compressed or pounded down.

I'd like to understand what happened and what I can do to prevent it from happening again. This spurs a few questions:

1) Do I chock it up to defective glycol bearings? They were purchased 2.5 years ago from a reputable vendor, but likely newer stock.

2) If I can find early non-defective glycos am I still putting too much strain on them cranking 270hp through 2.2 rods and their associated bearings?

3) Would going with a clevite bearing or other glyco alternative prevent something like this from happening?

4) Is there any benefit moving from the 66mm crank and associated rods to the 70.4mm rank and rods? Obviously there are performance implications, but I'm more curious about the rod bearing strain and whether or not this is a safer route?

Since a picture is worth a thousand words here are a couple for you: