Sure you could pull it off... but you'll notice I didn't say your fish will live. All joking aside, no, don't do it. They are kept in seperate tanks at the LFS for a reason. Besides you could only fit about 2 goldfish in a 30 gallon tank, no room for angels.
For one I doubt you have the room for angels as far as height and depending on the goldfish they will get quite large and are COLD water fish as mentioned that is why they thrive so well in ponds ....