Cast Iron Closet Flange...

[jedfsu]

Hi,
I am in need of advice about my cast iron closet flange. Yesterday, we took my Standard Modernus off as there was rust coming from under the toilet. Home was built ~1925 and once we got the toilet off, it seemed that the wax ring was more than likely the original! Needless to say, the original cast iron flange has partially broken off (or rotted off). The closet flange and pipe are one complete piece. I've purchased a 1/2 moon spanner flange that is supposed to arrive tomorrow. I'm told that I can put this under the section that is broken off in order to have a place for the back left bolt. I just want to make sure that I'm not going to have problems if I don't have a whole new flange installed. Am concerned whether or not the spanner will solve the problem of where to put the bolt. Also, portions of the inner part of the closet flange have also rotted off. I ordered a fluidmaster wax ring that is specifically for older toilets from www.deabath.com which is not the standard 3-4 inch that HD sells. What do you all think? Is this going to function properly or am I going to have more leaking issues? Clearly the old closet flange has seen better days... Am attaching 2 pictures - I've marked one where the inner raised portion of the flange has rotted off.. thanks in advance!!!