Fortunately, the reinstatement is fairly straightforward. See 61.199. You fill out an 8710 and take a practical test for either one of the CFI ratings you previously had or for a new CFI rating.

One of the advantages of the "old" rating is that the DPE (it's not an initial, so I'm pretty sure you can always use a qualified DPE unless you want to use the FSDO.

Look at the CFI PTS. There's a table for renewal and reinstatements that covers a much more limited set of tasks than the full ride and many DPEs are far more liberal in the way the handle the reinstatement of a CFI who has already shown that he can do it.

Bet bet is to ask around locally about the DPEs who handle these regularly.