Salts CaSO4 3.2g, CaCl 2.0g, MgSO4 pinch, NaHCO3 1.5g plus half a tab of campden. Lactose at 15 min.
Based on boiling 7.00 gallonsliters at 1.062 for 30 minutes, this will decrease your wort by 0.50 gallonsliters, bringing your after boil OG to 1.066. You wanted an OG of 1.071. It looks like it will be under.