I keep my Jax at ambient temps around 75 to 78ish and he seems to do fine. I was worried it would be too warm for him, but any cooler than 75 and all he does is bask all day.
I keep his basking spot at about 84-86 and that seems perfect for him. Basking only in the morning and after a meal instead of all day.
I'm sure every cham is different, just like people. Keep an eye on him for a bit and see how he does. If he seems uncomfortable, you may need to drop it a few degrees.