The LS7 valve issue is more on 09 to 11 z06s...I have an 09 Z06 with 12000 miles, and had at one time read every every thread on this issue. Hib Halverson has an article updated since our Z/28s made the scene. Our engine changes are in page 18 to 22 ( or so).
I also got a GM 7 year premium warranty just to be sure. So no work on mine until 2023. One last comment on CF, they have good information, but they love to post excessively.
https://www.corvetteactioncenter.com...-7000-rpm-ls7/