I would go with 86 deg, 89 is a little high. I would continue adding salt until you hit 2 TBSP per gallon. If that is ineffective, use a half dose of quick cure. This is my exact treatment method. I have lost one loach to ich in two years, and that one was skinny.
They were fine until I moved them. I only bumped the temp to 86 yesterday and it's at 87 today, so it shouldn't be too high. I also increased the salt last night (only by 2 tbsp in 10 gal). I hope the other one pulls through. I'm not sure if the quick cure will help at this point. The weird thing is that when they were in the 40g, the only other fish that got ich were tetras. There were 5 other loaches/botias in there as well as a couple bichirs and none of them got it and the clowns had ich for probably 3 weeks. I have only lost one fish to ich before, so this sucks.