I would be very concerned about simazine carryover into the chickpeas, esp at the 2 lb/ac rate, and especially with only 7" annual rainfall.

For rotational concerns (with chickpeas), I would try the Cyanazine/Bladex first - see if that gives you the extra grass control you need. 

Sometimes, I use a post-emergence grass product called Option (From Bayer). It can rotate to any crop in 60 days (if my memory is correct).  However, I suspect you don't have access to it, if you don't have access to all those other products.

Another product that comes to mind is Basis.  However, again, I suspect you don't have access to it either.  Is that correct?

While I am thinking, maybe you want to try some simazine on fields which will be corn this year, AND next year.  Then drop the simazine in the last year of corn before you rotate out.  I don't know if you have this kind of flexibility, but I thought I would suggest it.