I wouldn't do it. The betta will see the angel as another betta, due to the long flowing fins. This will be rough on a smaller angel. A larger angel, being a cichlid, won't tolerate that sort of behavior, and will tear up the betta.
I have 2 large 5" long angels, 5" high and added a standard betta, there was some following for 2 days, but everything is fine. I supose its the temperate of my angels, they're very placid.