I have some experience getting guys ready for a Flight Instructor re-examination, so let me give you some advice.

The regs are very specific about what needs to be done. FAR 61.199 spells out exactly what needs to be accomplished. You need to pass a practical exam for ONE of the the ratings listed on your expired certificate. After successful completion of the ONE exam, you are granted privileges for all the ratings listed on your expired certificate. You choose the rating (CFI,CFII,MEI) with no endorsement required.

I make this point because some DPE's feel that they have the right as well as the responsibility to exam you on any subject matter pertaining to any instructor rating you held, and this could not be further from the truth. I have had several converstions with the Feds on this very subject, and they have always confirmed that these DPE's are operating outside the bounds. Make sure that whom ever you choose to do the checkride with, that you get this out in the open and see what they feel they can examine you on. If they are one of the above mentioned DPE's, find a new examiner.

Previous advice about doing the CFII is well worth taking. Good luck.