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I would add about 2/3rds of the suggested amount, give it an hour to mix with the pump running, and then test the water to see how you are doing. You don't usually want to make large PH changes all at once. Calculated amounts for PH changes are never exact. It is better to go slowly than the overshoot.
By the by, what do you use as a source of chlorine, and what are your other test results? Depending on your source of chlorine, and your current TA level, you may want to approach this in a different way. For example, with a SWG or a very high TA level you would probably only want to raise the PH to 7.2 and then let it drift up on it's own. On the other hand, if your TA level is very low or you use trichlor as your source of chlorine you might want to use soda ash instead of borax.