Interesting TL, but i have some questions:
1- In the organization of the provinces, where was assigned Syria? It wasn't better made it an other province, maybe with Cyprus?
2- About the province of Greece, you talked of the Greek lands in hand of Macedonia or all of Greece proper? The Greeks were allies of Alexander, and i guess they will refuse to relinquish their indipendence to him...
3- It may be controversial to proclaim a Macedonian empire and then build a capital in Persia... I guess Alexander chose more Babylon, were also was the tomb of Ephestion, or maybe build the capital in Mesopotamia... suggest OTL Ctesiphont or Baghdad.