It is a JOB. A couple of suggestions... while you're at it replace the waste and overflow and if possible the tub/shower faucet. Second, you can get tub surrounds in two pieces that will fit through doors and Three (I like the Sterling brand surrounds), American Standard makes an *Americast* tub that has the properties of a cast iron - but without the weight. I personally prefer Kohler cast iron over Americast as I think it's more durable. BTW you can break out the old cast tub with a sledge hammer and cut up a metal tub with a Sawzall all.