you will have problems putting a large angel in a small tank, especially if it is uncycled.
I would try and put some sort of divider between them, a piece of glass or perspex, a sheet of thick plastic, even a sheet of netting... TM should find you a result quickly, big angels are popular, just don't mention about sexes
or try your LFS, they may be interested in doing a trade with you.
what area are you in?