I agree, angels at 76 - 82F...
Be forewarned, that while the fish may appear to be doing well in the colder water, the wrong temp for the species of fish can cause a lot of internal organ damage, and also cause some of their internal organs to simply give out after a period of time. The chances are huge that the colder water will decrease their life span by quite a lot.
Other note... you don't ever want to fluctuate the temp the was it was suggested... the temp change, especially something that extreme would put the fish's body into shock and kill it. That's very dangerous.
Tropical fish are WARM water fish... and is why they are termed as "tropical". Some fish can handle a wider range of temp than others, but angels don't typically thrive in such a low temp.