I have them in both of my b-bodies. It's been pretty well documented on ISSF and other places. There's a bit of work in getting the rails and the seats mounted to the floor but there are multiple solutions.
I love the seats. They are fantastically comfortable, and if they aren't, you can change absolutely everything about them.
The ONLY gripe is that sometimes the electronics in them can be a little flaky. From what I hear, NASA used these in the space shuttle too..