I did that over 20 years ago, and I believe the bolt that connects the "link" to the brake pedal is a different dia. and I placed a bushing in there to take up the slack. Other than that, yes it bolted in and I installed a 440, headers, with no clearance issues. Good luck.
If you need a bolt pattern measurement for the Kcar booster let me know as I have one sitting at home and can post the pattern measurements here for you. I dont know the bolt pattern measurements for the 81 doba but the earlier A, B and CBody were different so the holes have to be elongated on those cars to use the Kcar booster. (I can provide those measurments as well if you like)
I'm putting a stroked 400 in a 81 Cardoba & was concerned about clearance problems with the brake booster. The car will be street driven & I'd like to keep the power brakes but was considering changing to manual brakes if I had to. Thanks for the info guys you've been helpful.
Sorry I didnt get the chance to get them measurements last night but now I'm not sure you need the measurements or not... if you do let me know and I can