Richard, I find it interesting that your blueberries have been so successful with a pH that high, it makes me less worried about growing mine in ground with a native pH of 5.6.
We don’t grow northern blueberries here – they’d hate the weather. Instead we have ‘rabbit eye’ cultivars (e.g. O’Neil) and proprietary hybrids (e.g. Monrovia). The latter is incredibly tolerant of near-alkaline pH while the southeastern cultivars are fine with pH near 6 – although they do best in the mid to upper 5’s.
Duly noted Mr. Richard. The Sunshine Blues are evergreen you say; do they still need chill hours?
Monrovia recommends 150 chill hours for Sunshine Blue.