I've never shattered a KB hyper.
Who here has shattered a hyperutectic on a good tune?
Who here has shattered one from too much timing on pump gas street/street driving?
You can ping them on unleaded and they'll take it for a while, longer than credit is given.
I've hammered mine in my 410 during the tune process a few times, no issue.
I did have a spacer gasket leak that caused idle speed drop, fixed that.
I'll say like this...
The last 5 motors i built and sent out into the world were all KB hyper piston equipt in the 9.6-11 compression, "2 360's and 1 408" were quench domes with .028-.035 quench, the other 2 are KB243... one a 318 bored to 4.040 and the other .030 over 340 sitting in the late spinmans '69 dart which he rode hard and put away wet for a yr or so before he passed into mopar heaven. To this day...no issues.
It's your money...so what keeps you from spending it on what "some" say are the "best",
Is it common sense by chance? ;)
