They will be fine. I bred all my smaller angel pairs in 20g highs and my large pairs in 29gs. The more taller and narrow the pot the better. When I bred angelfish I used spawning slates. I found they take up less space and its easier to pull and artificially hatch the eggs in case the parents start eating the eggs. I used similar slates in the picture I found on google. I bought a pack of 10 at a local fish swap for a few dollars.
If you have any questions about spawning or rearing fry feel free to pm and ask me any questions.