Opening Draw On A Bent Pipe. How?

I've tried to open up an airway on a bent pipe before and failed miserably. Straightening out a bent stem made out of vulcanite, ebonite or the like is simple enough. I've used a heat gun to make the stem material pliable and the memory in the material helps to straighten itself out. Simple enough. The hang up I ran into was during the actual re drilling of the stem. Straightening a bent stem doesn't mean that the hole that was previously drilled in it is perfectly straight. Trying to work a wider drill bit though a straight stem with a wonky bore hole is disastrous. Cracks and breaks in the stem during the drilling process are inevitable and I have the broken stems to prove it.

My question is, how would I go about making sure the original bore on the straightened stem is perfectly straight so I can carefully get a wider diameter bit through the entire stem without breaking it?

I thought of putting a straight wire through the stem after the initial heat and straightening, applying more heat to the stem while carefully working the wire through. I'm thinking twice about this because it may warp the hole even more.

How do the pros do this correctly?

I have a pipe that's been laughing at me for years. I opened up the hole in the stummel and broke two stems while attempting to get this done. I'd like the practice of properly straightening a bent stem and widening the diameter of the hole. I would like my pipe's respect back and I would like to smoke it.

Any advice would be wholeheartedly appreciated.

Thank you all for the input. I wish I was closer to a good pipe repair person so I can get some lessons every once in a while as I'd like to be able to do these things myself. I am sort of a masochist. The greatest growth comes through pain. In the case of pipes, the pain is mental rather than physical.

I'll take this project again shortly and heed George's advice about individual shorter questions. I'll post them to this thread with pictures and hopefully we can end up with a thread that takes us through the whole process successfully... either that or we'll have a thread of broken stem pics and a reference for what not to do.