FAA CFI-II-ME
I'm in Ottawa and have both Canadian and FAA CFI-II-ME.
Just renewed my Canadian and an Class 1 aerobatic instructor recently.
I will be doing a ride in the US shortly for the purposes of "revalidating"
the FAA CFI-II-ME.
Read FAA AC 61-98B IPC Guidance.
Allow at least two hours on the ground and two hours air time which might well be in excess of what you would get for an initial instrument rating in Canada.
It is what is called "a solid evaluation of a pilot’s instrument flying knowledge and skills"
Swapping jurisdictions means you have to clearly know the differences between the two countries and it is easy to answer a question correctly for one country and wrong for another.
I sent you a PM.