I did exactly this about a year ago, with a current CRI and around 300 instructor hours. All I got was 25 hours TK credit for the T&L content. I enjoyed and needed the course and got a good skilltest pass, but probably actually needed 60% of the required hours to cover the flying syllabus. I did need most of the TK hours as there is a lot to learn about all the PPL syllabus individual lessons and their delivery.
I also nearly got tripped up because my FIC instructor didn't think I needed a pre-entry test, as I was a current instructor (and in fact had on one occasion instructed him!, albeit only for a type checkout so that he could then examine one of my students on that type.) That proved untrue also.
I subsequently learned that for people like us it is possible for the ATO to make an individual case to CAA for a reduced syllabus. Learning that was too late for me, but you might discuss it with your FIC school to see what's possible.
G