Not sure, check with the council.
We live in a heritage overlay area in malvern east...you can't change the front of your home, but you can extend and go up at the back, you can't demolish the house and develop the block. We have a heritage tree too...we apply for a permit and prune it every 4-5 years.
The Council will allow some of the younger houses to be demolished...mostly from the 60s and 70s but you need approval for the new home design, it would have to work in the area.
We don't find it too restrictive and it protects the mostly federation homes.