Regarding the 45% being Albanian Arvanite before the Turks, Google "Arvanites Helsinki," they cite Greek scholars since I am not sure I can post a link here. You can also Google for this "The Ethnoarchaeology of a “Passive” Ethnicity: The Arvanitesof Central Greece"
Regarding the rest: 1700's is way too late Debbie. By then the Greek Church was one with the Turks, 'hellenising' Albanians, Bulgars, Slavs, Kurds, Arabs, Palestinians and god knows who. The fact is that a 'Greek' is an Eastern Orthodox that belongs to the Greek Church and has been that way for 1500 years. Not all converts kept their modified last name. Instead of Boulgaoros they might have chosen Ierounous or whatever, losing their link to the past. This is the truth, and this is why Greece doesn't do a census based on ethnicity.
Greece in 1820's: You a Christian? Ok, you are a Greek. Now learn Greek and read about Homer, your direct ancestor. 'Greeks' were clueless about the ancient Greeks, they called themselves Romioi, after the Romans!