Switch to manual brakes makes car run better?

I wasn't sure which sub-forum this belongs in but here goes. I finished converting from power disc/drum to manual a few weeks ago and love the manual brake feel. I also installed a new 15/16 master from Dr Diff. Car is a 73 Duster with a 74 318 smogger with Summit K6900 cam, Performer intake, 600 Edelbrock carb, decent advance curve, and duals off the stock manifolds. Drivetrain is a 904 with stock converter and a 2.76 rear. It's obviously no race car. It seems like I have more power and better throttle response after the brake conversion and I'm trying to figure out why. I've got a few ideas but would like opinions from people much better at this stuff than me. 1. Ported vacuum advance adding to the timing curve due to no vacuum lost to booster. (Booster was possibly leaking vacuum?). 2. Better stronger vacuum signal to the carb. 3. Fuel curve issue on some cylinders due to the location of the booster vacuum tap on the dual plane intake although the plugs have always looked the same between cylinders. The most obvious to me was more brake drag before due to some booster/master/brake pushrod issue but the car seems to roll the same in neutral as before and coasting while driving seems no different. I also had never noticed any lining smell or abnormal brake heating. All I can think is that the change in vacuum fixed a tuning issue I didn't know existed. If you took the time to read this short novel, thanks for any and all thoughts. I feel like I made a "demon tweek".