I have a cast iron toilet flange that has rusted out and must be replaced .
I plan on cutting the verticle waste line under the sub floor and putting pvc pipe and flange in place of the old one.. my ? Is what is the most inexpensive and efficiant way to make the connection.. is there any way to connect a pvc coupling to a cast iron pipe ?/
Or do I have to put a cast iron coupling with treads on one end and screw a threaded piece of pvc to that and go from there? Or can I just use rubber sleeve with hose clamps to connect the pvc to cast iron and set the flange to the subfloor to stabilize the toilet?
Also is a right angle grinder sufficient to cut the cast iron pipe with out too much effort? Any help would be apprieciated I am doing this for an elderly single women on a fixed income who otherwise would not be able to afford to have it done.. she is suplying the parts and I am doing the work for free since she is not able to afford a plumber..

Cut the cast iron raiser, with your grinder, leaving a few inches of pipe. You may now convert to PVC using a shielded metal clamp. (see image). Good luck, Tom