NO ONE is going to permit you to take a Python apart before purchasing it. There is too much risk of damaging it and this is really only recommended to be done by Colt.
If you are just looking for a nice, blued Python, I'd suggest looking for one manufactured in the late '80's or 1990's, because:
1. There is a better chance you will find an almost new in box Python
2. There is less likelihood that it's been beat to death or refinished.
3. It will probably have the proper grips, box and stuff that goes with it.
4. You won't be paying a premium for a nice '60's or '50's Python (good ones hard to find)