80 is at the upper end of what greens should be kept at, honestly I would try it with your jds. Just keep a close eye on them. I think their aggression levels could be similar, and greens can be very interesting, colorful fish.
Not all greens are super agressive, I have one who is by far the bottom man on the totem pole. I kind of feel bad for him. Right now he is probably the smallest sunny in the tank and takes a bit of heat from the pseeds and bluegills
Just try put the green sunfish with the dempsey cichlids to see if he can get along with them. Green sunfish are highly adaptable so 80F temp should not be a huge issue for him.
Just wanted to update this thread. I added the sunfish to my cichlid tank 2 days ago. He is doing really well! I'm glad he is getting along with everyone! Only my GT seems to be picking on him a little bit. I almost wish he would stick up for himself against the GT lol. He's one of the biggest fish in the tank too. I'll have to see if I can get some pictures of him later. Thanks for all the advice and encouragement! He's a really cool fish.