What top ring gap were you running?
Ive pulled ring lands off like that when i have messed up the ring gap and had it too tight
I honestly can't remember as I built this 10 years ago. I do know I ground them to KB spec but can't remember the exact gap.
Would a stiffer spring really help? I've never heard of that coming into play but I don't claim to know everything. I am replacing the springs, and heads for that matter. I've got a pair of aerohead reman heads with 2.02s and .509 lift springs that will be going on this time around. I've also got a MP 292 .508 purple shaft that's going in too.