7.6 is actually a nice starting pH, and 8.4kh is fine.
When you achieve a ~30ppm CO2 saturation you should put you in the 6.6-6.8 pH range. Very nice for a whole lot of fish.
With 8.4 kH you could dilute it down with some r/o if you wanted to keep south americans in a more "ideal" water.. but 8.4kh is great for rainbows and africans too, generally.
So no worries, you have nice water to work with.. very middle of the road.
My tap is 8.5+ph 1.5kh .. a pain in the ass.