conversion of overseas Instrument Rating
Fudwinkel
To convert an overseas Instrument Rating to Australian CIR you will need to sit for the Australian IREX written exam. If you have passed the exam previously as you mentioned this will count and you will not need to repeat it. You will then need to do enough flying to reach the Australian competency standards for CIR flight test (multi or single as appropriate).
The same process will apply to N9537q.
N9537q suggest you look at the bigger schools for assistance, ideally organise some back seat flying so you can gain some local knowledge and practice at "no cost" before you embark on your own training. It is very helpful in your situation.
good luck
OZ