Here is a link to a 2wd blazer that got the full frame treatment.
http://67-72chevytrucks.com/vboard/s...d.php?t=194823 It shows what is needed to a C-notch. To answer your question if you install the kit right it is plenty stronge. Yes they are rare and yes it might be a shame to cut one at all but it is your ride and it will still hold its value (maybe more) if it is customized corectly. I have the rariest of all a 70 2wd and it is in line for the knife right now! Do what you want to do but do it right and do it safe. For the Keep it stock guys remember a C-notch can always be reversed by a good Fabricator and you would never know it!
Kevin
LFD Inc.