I bought a whole kit from dr. diff for my 68 charger and was very impressed at how well it bolted together and how it worked. He helped me identify my existing booster because he said a dual diaphram booster would work better in my application.
Turned out I had the single. How many guys would have told you that. And I probably wouldn't have been happy with the pedal pressure to stop if I would have stayed with the single.

Bottom line it stops like a modern car now.