'67 Dart Brake Booster?

If you find the answer let me know. I had my parts all order by a guy I was seeing (not anymore, hence i need help) and he ordered a 75 valiant power booster, but it won't bolt up even close to the same. It would involve complete firewall modification as well as under the dash for connection to the brake pedal and moving things around for it to fit too! I am trying to find a simple master cylinder that works with disc since i just did the conversion and my old one wouldn't be sufficient plus it was leaking.