Disc brake swap

[Mike harris]

I did a disc swap about 2 years ago but they've never really been that good. It was a master for 70 c10 disc swap, I have added a vacuum canister but it made no difference. The brakes work to an extent but I can't lock the car up. Booster is working fine but the pedal travels half way then it feels like it hits a wall and can't push pedal any further no matter how hard I try even with my size 17 boots on!!!. I disconnected the linkage to see how far the pedal should go before it stops and has loads of reserve travel left. Has anyone had a problem like this before? Or have any insight as to what might cause it? Wrong master? single booster not enough? Need a heavier boot? Thanks