Plug readers: What would you do??

Setup:
Gen3 Hemi racing motor NA 13.5:1 compression running on 110 racing fuel which has purple dye in it.
Holly Sniper 4500 TBI fuel injection and Mopar Drag Pak intake. Ported Eagle heads. Brisk ER14S plugs.
After 5 passes it slows down by 20 numbers and the plugs look like this:
left bank (2468):
LeftSide.jpg
And they look like this after a quick clean with a wire wheel:
LeftSideCleaned.jpg
Right bank (1357) Looks like this before cleaning:
RightSide.jpg

I clean them all and put them back in and the car runs it's number again.
1. Too rich?
2. Why the difference between banks?

Would you clean them and keep using them (what I've been doing) or replace them (these plugs aren't cheap, $180 for a set and there are only 2 companies making a cold enough plug for this motor) or something else?