I am replacing the floor in the second story bathroom and the current height of the flange is not high enough. Currently it looks like some something made of PVC with a metal ring inside the iron hub. I've attached pictures, sorry not the best and I know I should have cleaned the rest of the wax seal off. (Or cleaned more in general) My question is, what is the best way to raise the height with this setup, replace, extend? I need about 1/2 of an inch.