Replacing Cast Iron Flange, Not enough concrete to anchor.

Looking for advice,

My previous Flange, one whole side was gone, no place to hold closet bolt.
Therefore I removed the Cast Iron / Lead installed flange.
Tile floor is not quite level, but my wife does not want to replace it at this time.
I found a cast iron compression flange from Jumbo, as I have a fear of using Plastic since the tile floor is not level.
My thought is that if the Cast Iron Compression Flange is secured it will have less movement.

When I place the new compression flange in place, I can get it to set on the Tile, but I can not secure it to the concrete.
In other words the hole is larger and was packed with some type of rubber material holding the previous flange in place for the sweating process.

In summary, it appears that the previous flange, secured with Lead, did not have any anchors / tapcons.
Is it acceptable to just tighten the compression flange to the pipe with the flange setting on the floor.

I guess my other option would be to pour patching concrete, leaving room for the Compression Ring,
my assumption is that the Tapcons may crack this new patching pour anyway with it being such a small amount of new concrete.

Thanks in advance for the advice.

If I just need to hold the closet bolts, and can use a ring like this
I use screws on wood and for tile with concrete, a rotohammer with 1/4" drill bit and anchors.

I was going to consider that but felt that the stress might be too great. So at this point, I did completely remove the old flange.
At this point just trying to determine if I need to anchor beyond the tightness of the heavy compression flange.
It feels very solid once I snug up all four sides of the bolt.