Plastic Collar If I Cut A Cast Iron Soil Vent Pipe Can I Put A Collar On It & Then Build It Back Up In Plastic?

If i cut a cast iron soil vent pipe can i put a collar on it & then build it back up in plastic? - plastic collar

Iron, I try to move the toilet in my bathroom, but the ground is vent pipe is cast and the dress facin the wrong way, so I cut the pipe, then build again in plastic. I am confused help please !!!!!