$100? Not likely in this day and age.
I have a 67 Chevelle convertible and my disc brakes are from a 72 Monte Carlo. I got all my parts for the conversion from junkyards 20 years ago. It can be done today, but will take alot of effort. You'll need the spindles, calipers and master cylinder. I'd change your rubber lines too. Don't bother trying to find original 67 disc brakes. You'll pay twice as much for the parts and they aren't as good as 68 and up.
I would also suggest going here for all the Chevelle info you can possibly stand. Great bunch of guys and they can talk you through ANY issue on any Chevelle. <a href="http://www.chevelles.com" target="_blank">Team Chevelle</a>
<a href="http://www.mdesignstudio.com/chad/other/mychevelle2.jpg" target="_blank">My 67 Chevelle</a>
[ November 07, 2002: Message edited by: Django ]</p>