drop spindles and 2 clicks on the rear probably isn't gonna sit level. i'm 2 clicks out back with drop spindles and adjusters up front.
personally, i'd raise the rear back up to stock, install the drop spindles up front when they arrive, then re-do the rear to match the amount of drop you obtained in the front, then go tire shopping.
here's a great tool:
this allows you to compare different tire sizes and will also give you the overall height of a tire to also aid in dialing in your ride height/tire space/etc.
and a local tire store isn't going to be too much help to you i'm afraid. they want to sell what they have in stock or what they can get thru their supplier and most of the time they won't be able to get you common aircooled sizes like 135's or 165's (for a decent price that is).