I did remove my "popcorn" insulation recently for a complete Surfside
1980 rebuild. It was just two gross to look at with cracks and discoloring from leaks
in the belly band and so on.
It was pretty easy to remove with a spatula, and then the rest with a wire brush. I did not even think of asbestos actually, just wore a dust mask for it.
I attached a picture of what my insulation looked like.
I'm not sure yet with what to replace. Lucky for me I have the Trillium
Outback builders here in Calgary and they will provide me with the materials they use. Some kind of foam and then marine liner on top.