I am remodeling a bathroom in an old house. The floors are concrete, and right now there is just what looks to be a cast-iron waste line that runs up through the concrete for the toilet. The inside opening of the pipe is 3 1/2" in diameter. What flange do you recommend for this? I can only find 3" or 4" - one is way too big and the other is way too loose. Please help - Thanks!
Matt