You definitely don't want to use trichlor tabs or any more dichlor to shock--you don't need your CYA levels coming up any higher than that for now. My understanding is that ideal CH for plaster pool is 200-400, so I think you're right on the money where you are. If it were my pool, I'd go with bleach, or even better, liquid chlorine if you have it available to you (it's the same as bleach but 10% concentration and sold in bulk). With a CYA of 60 it will take a good bit of bleach at the beginning to get to your base target, but the upside is that it will last longer so you probably won't have to add it everyday. You're going to have to maintain your Cl no lower than 5, and up to 10. It will take a few days of testing morning and night to see what your Cl consumption is, but I'm betting that you only will have to add every 2nd or maybe even every 3rd day, if you maintain it on the higher end of that range.

Janet