I had a flame angel in my 75 fowlr
before I added my raccoon butterflyfish. I too was real worried that my flame would bully the raccoon but they ended up being buddies. I guess I got lucky with my flame angel. Not sure how your other fish will treat him though, but a great fish, adds a nice splash of yellow and loves to swim.
Oh yeah, in case you didn't know already, they can be real finicky eaters at first. Just be ready with some fresh scallops or shrimp from the grocery store. Chop some up, soak in garlic, and then rubber band it to a small rock. That's the only way I got mine to eat during the first week I had him, then i got him to eat flakes out of my hand. They really seem to like 'stationary' food.