Need a full set of parameters to effectively help you, but here is my suggestion.
First order is to get your TA to 60 (do likely several rounds of acid to reach pH=7.0, let pH rise to 7.8, repeat acid dose, do until TA=60), then maintain 7.8 max. so you are not scaling. Your pH ceiling will be 8.06, so you'll be chasing it a bit.
Long term CH=1200 is not sustainable, so think about several rounds of water release and refill. I'd do 10% at the time, let it intermix nicely, restest CH to see impact and target at least CH=800. Keep TA=60 so you chase the pH as little as possible.
Even then your reasonably sustainable target would be more like CH=600 and TA=60 so you can achieve pH ceiling close to 8.1 and not chase the pH forever. I personally run CH=450 and TA=60 in summer. Winter CH=550 and TA=60.
I understand you might still be under water restrictions, so do what you can to get water reaplaced partially. What's the TA of your fill water? if below your current TA, it will help you get to your goal more easily.
Good luck.