Macrophylla is actually a hybrid that occurred naturally in both the Cebu Islands, and the Philippines.
I think you will have a difficult time with Macrophylla in Savannah. Macrophylla is normally used as a root stock for lemons, and seldom grown for the tree itself. The University of California states, trees on Macrophylla have poor freeze tolerance, much worse that that of trees on any other commonly used rootstock.