A pH of 7.6 isn't very high at all. Many people would kill to have that kind of water out of the tap! Besides, once properly acclimated, the majority of fish will adapt perfectly well to a wide array of pH values, even above 8. The most important thing is a steady pH. Plus, many of the places that "suggest" a "proper" pH are giving values based upon the species native conditions if in the wild. Most fish we buy never even see the wild, they are tank raised and are therefore raised in conditions unlike their native habitat. Today's bettas are very, very different than true wild bettas...so they don't need the same parameters.
Of course, a pH of 4 or 9.5 probably wouldn't do too well to house most fish in, but the acceptable range is much greater than 6.9-7.1

Many people keep "traditionally" soft water, low pH fish (such as cardinals and neons) in a pH of 8.0 or above
Glad he's going into a 10g - he'll appreciate the room. Gonna have a filter/heater for him?