Hard Brake Pedal poor stopping Manual Brakes
 

Any advice will be greatly appreciated!
A few years ago I had brake work done on my 68 (manual brakes) and they haven't worked right since.
The work done was comprehensive and involved replacing the brake lines calipers, rotors, and master cylinder,
Since then I have been experiencing a hard pedal and decidedly poor stopping power.
I decided to tackle the problem myself so here's what i did :
I removed the master cylinder and discovered (via the bore diameter) it was incorrect and was for power brakes...... So I thought, problem solved! I replaced it with a manual brake master (I verified the bore width) but the poor braking issue still existed so next I replaced all 4 calipers , new rotors proportioning valve ..... Still same issue .. hard pedal ...... poor stopping power.
I've had and driven the car for over 25 years prior to the original brake work (which i had done because the car had sat for several years) the braking had been fine. Yes I know there is a difference
between power and manual but trust me, there is something wrong.
Thanks,
John

My first question is what type of brake pads are installed? With manual brakes you need a softer compound.

Presently, Semi-metallic but i had organic pads prior and had the same issue.

You have me thinking now... I wonder if there are different calipers for manual brakes. This is an interesting issue, I'll check back in a little bit.