Normally I disagree with Riki (sorry Riki), but here, I'm with him.
I don't believe that we can call anything "standard" unless there is a specific piece made by GW. Mods of that would then be non-standard. In all of my games, I have never seen the flamer used to represent the Targetting Array (even though it is a great idea). I, personally, used the target lock to reprsent the TA because I don't use TLs, and I like the look of that bit.
As long as you are consistent across the army (i.e. all the TAs look the same), then you can make them whatever you want if the piece doesn't exist by GW.
Just my two cents.