I heard a wonderful little statement a while ago that I really like - more for it's shock value than anything else, since it really made me stop and think. It says:
I asked God to give me what I deserve - so he slapped me and sent me to Hell.
What I really love about "pure Mormonism" is that it posits that, in the end, there really is nothing that is required except your best effort to live according to the dictates of your own conscience and understanding - that mistakes are fine, as long as they are made in sincerity. (There's a lesson in there for how we view our leaders - past and present - at all levels.) If that's true of those who never heard the Gospel, it's true of those who did.
So, my answer to the title question is simple, but not easy:
I go with what seems like the right thing to me personally and trust that God will accept my best effort.