I'd be interested too, I've been reading up a lot on the Achaemenids lately. I have that "What If" book that's written by a bunch of professional historians, but quite frankly it's a pile of crap. Their scenarios on Persian victory mostly talk about OTL history and one scenario went on about how Greeks championed freedom and equality against the despotic orientals whereas the other took the butterfly effect and trampled it into the ground as it left it behind. I don't think many professional historians are capable of critical thinking, to say the least. Still though, one of the scenarios did touch upon an interesting premise, Cleitus could've been a second slower to spear a Persian noble by the name of Spithridates and Alexander's whole war effort would've been halted early as a result of an axe plunging into the King's head.
In any case, off the top of my head I think ImmortalImpi's written a couple of good Persia TL's.
The Persian Peace is probably along the lines of what you're after, it takes place in Sassanid times.