Hi, I have a 47 UG with two angels, I wouldnt consider more than one or two more. I think a tank looks more healthy with two to three large fish and some smaller interesting fish, rather than lots of large fish crammed in. I keep mine with Apistogramma, tetras and a few catfish and all get along fine. If you want small angels, 5 or 6 would be a good number and then allow them to pair off, you could be lucky and get two pairs or just one would be good, you could then trade in the others for rams, apistogramma etc which are colourful and full of character. Angelfish will fight among themselves as they get older so a mated pair is the perfect solution.
Ken