My full grown angels body was baseball size. Maybe larger.Thats without fins.
And IME you can be successful with two in a 30 But the only other fish I house them with are bottom feeders. I also leave a lot of swimming room.
It can also be really hit and miss trying to get two to live together in a 30 without fighting. They are really hard to sex without their breeding tubes exposed and for me it's tricky to even pick out which ones have paired up at the store. I currently have an angel that was partially blinded by the other one I had in there.
All that said, they are very interesting fish. They always come to the top to beg for food when you come by. And if you can get a pair to spawn it adds a whole new excitement and dynamic to fishkeeping.
I'd wait for the bigger tank. Bigger tank is ALWAYS better