<VV> exhaust stack question

[judynrandy at comcast.net]

To change a rusted into oblivion exhaust stack on a corvair head, is it as simple as twisting the old one out with a pipe wrench, twisting out the replacement one, then put the head into the oven (when the wife is gone, of course) at 350 degrees for about 10 minutes while you've already put the new stack into the freezer for a while, then remove the head from the oven and while still hot slide and tap gently the new stack into place?  Inquiring minds want to know.  If there is an easier way, i'm all ears. 
  
Randy (Cap'n) Hook 
Hopewell, PA