Well I stand corrected. I guess the drought has created enough demand for RO treating in TX now. This is news as far as I know. With your fill water however, you wont need it for CH at all. I am as water conscious as anyone, but an RO treat may not save enough water to make it worthwhile. It all depends, but I have more questions about RO pool treating than I have answers. I'm very familiar with large industrial RO units, but have no idea how these pool treat units are sized, staged, or what sort of rejection rates they run. All that said, he is right, work it down with gradual drains.
You have Calcium from Calcium Hypochlorite your pool service used, or you put in unknowingly. It otherwise only comes in with your fill water, but your test showed it pretty low (130) compared to your pool at 600. Are you on the Edwards Aquifer just curious? You can work CH down with your fill water easily. I hate to waste water, but in time you can get it down and work with what you have now. You just need to pay some attention to water balance and CSI with the Pool Calculator. Plug your numbers in, and it will tell you if you are in trouble with scaling potential. Remember, pH is very important in this, so keep it on your radar screen.
The 70 CYA is better, but I would work that down to 50 and see how that does. If you run 70, it will take a ton of bleach if you need to SLAM. Reaching 50 isn't much further, but I would do that if it were me. If you lose too much to the Sun, you can work it back up to 55-60. That is the route I'd take to start. Just make sure you don't add any more with Dichlor or Trichlor products.