Okay, here are a few suggestions, generalizations, and thoughts off the top of my head in no particular order.
Since the recoil generated by the 6PPC is pretty light, you may not have a problem with cheaper scopes failing, but I’ve always believed “you get what you pay for” and consider the Weaver T24/T36 good scopes for the money.
The T36 on a pistol will be the most difficult to master because of the high magnification in conjunction with the diminished field of view and lessened brightness of a Leupold, Nightforce, March, etc.
I think 16x is the minimum for serious accuracy work but you’ll get many opinions for either more or less.
You may want to consider a variable scope if there’s any chance you want to use the pistol for other than the bench or want to work your way up in magnification. With a T36, the gun will be pretty much useless for anything else unless you become very proficient with it.
I hope your break open Contender is a G2 or Encore variant because the backthrust generated by a case with the head diameter of the 6PPC is not safe in the old style Contenders. I have more info if you need it.
Trigger and headspace issues with the Contenders also need to be investigated if you want to strive for ultimate accuracy with this type of firearm.
Here’s one of the best forums on the net for pistol specific questions on shooting break open firearms:
http://specialtypistols.infopop.cc/eve/ubb.x
Another good source of info is Mike Bellms site:
http://www.bellmtcs.com/TOC.htm