brake question

[nvrdone]

my '49 3100 has the stock drum brakes at all 4 wheels. I decided to up grade & change the stock master cylinder to a mustang m/c with power booster. mostly to improve the stopping power and not worry about a complete brake failure if a line broke or wheel cylinder failed.
Big mistake. now the truck stops worse than it did before the change. I replaced all the lines with the same size as stock with 2 separate circuts. the kit came with an extension that needed to be welded to the end of the brake pedal short end to improve the ratio. I also added a 10# residual check valve into the front line.
Now the pedal goes within about 2" of the floor before there is any reaction and its scary to try and stop quick.
All the drums have been turned, new shoes installed and wheel cylinders replaced trying to solve the problem.
do I need to find a m/c with the same bore as stock ? any one have any ideas ? im about ready to install a stock m/c with out the booster.
thanks