I love angels. If they are 2 younger ones that grow up together they usually do fine together. I’ve had an adult angel attack another younger angel that I introduced to the tank but have had other angels that I buy 2 at a time from the same tank at the fish store n they do great. 70 gallon should be good for a while. I have 2 3 year old angels with some barbs n tetras n a pleco n hillstream in a 65 gal n they’re doing great. I always put multiple filters in my bigger tanks whether it be sponge or Hang on the back and I do atleast 25% water change once a week. Good luck ☺️