quote from you....
walker did say the the hi-flow water pump are junk!!!
quote from me.....
I was running a high flow Edelbrock and one head ran around 40 degrees hotter than the other. I put a stock pump back on and it cools much better.....both heads run the same temp again.
have you checked to see if both sides are cooling evenly? Do what I did, I put a stock one on for the heck of it and it fixed it!!!!!