I was curious when you started your post what you were going to say about fitting. It sounds to me like they're hit and miss, but sometimes you have to take into account what someone else thinks is good or bad. I understand that it's better to need to take some off to get it to fit than the other way around! Yes, you need to have some clearance between the tang and wood behind it - I don't remember he recommended distance, but one of the experts will be along shortly.

If you think there's something missing that should be there I'd contact the CMPicon - they're really helpful and will let you know.

It's great that it's already stained, but I hope you don't need to take anything off and mess up the stained area. I haven't heard of that. Maybe the new stocks fit out of the box(?)

Please let us know how it goes for you, and wish you the best of luck! I love 'C' stocks and it should look (and work) great.
~ Harlan