PVC pipe into cast iron waist pipe

Ok, I am replacing my existing drain pipe from my kitchen sink (from galvanized to PVC). My question is how do I get the galvanized pipe put of the cast iron pipe, and then what is the proper way secure into the cast iron waist pipe. Any suggestions will probably save me hours of work.

The galvanized pipe right know is stuck into the cast pipe with some sort of hard filler around it to seal it and lock it in.

If your galvanized pipe is going into a hub connected to the iron pipe, and the hub and galvanized pipe are in pretty good shape in that vicinity, I would cut the galvanized pipe a few inches before the hub and connect the PVC pipe to it with a Fernco coupler. That's my amateur opinion.

It's probably a threaded connection...use a big wrench, then put in a pvc threaded connection and continue to the sink.