I'm a rather new member so I can't answer at some points. I personally don't have read the Thundering Zeus (don't have seen it in the library I frequent) and especially read the French stuff so...

Tarn and Narain are a good base but a little exceeded, the actual specialist (about the numismatic evidences especially) is Bopearachchi.

Here a thesis on kingship in Baktria https://dspace.library.uvic.ca:8443/...amsey_2005.pdf