Think about diversity. With just 2 plant species you run the risk of an insect or disease which will destroy most of your plants.
I had a thing for Melaleuca Nesophilia. It had masses of beautiful purple flowers. The birds , bees butterflies and anything else that flew or crawled loved them. So I planted lots, well over 300 hundred anyway in mass plots. All my dreams came to fruition as they were absolutely spectacular in flower. Then a disease came, the name I can no longer remember or for that matter want to remember, and the end result is that I now have about three scragglly, motheaten excuse's for a plant with piddly little flowers.
Just saying. Go for diversity.
If you go to your library and get:
Grow What Where published by the Australian Plant Study Group.
Will be of great help.