Our house was built in 1946 and I'm replacing the floor in the tiny upstairs bathroom which just includes a small sink and toilet.
I took up the plywood underlayment down to the subfloor. The toilet was attached the floor by screws and instead of a wax ring that sealed the connection between toilet and sewer stack I found a foam ring. There was no flange as you would normally see in today's construction.
The pipe coming up from the floor is made of a very malleable metal. Not sure what.
I'm wondering if I can install the underlayment like it was before and install a new toilet flange over the sewer stack pipe opening (similar to replacing broken flange) OR do I need some special adapter? Basically the flange would bolt to the new floor as you'd expect, then I would install the toilet with a new wax ring to seal the connection between the stack pipe and the toilet.
What do you guys think? Is that a pro way of finishing the job or do I need a special part. Please see images for illustration.
Thanks for your help.