MASTER CYLINDER

The 1" bore may be perfect.And your Combination valve is the new distribution block.
Push-rod length? If the pushrod length is too short, then the pedal will have to travel some extra distance before it does anything hydraulic, and it may not push enough fluid out to affect any stopping action. It would be,in effect,be applying less than full pedal travel to the M/C pistons.
If the pushrod is too long, it is possible for the C-port to not be exposed enough to allow proper bleeding. Or if it is not exposed at all, then it will be impossible to pump fluid down the lines. The pushrod can be adjusted anywhere between too short and too long, but I don't like too-short cuz of the delay in engagement and the aforementioned long low pedal.
Since you had a hard pedal before the line swap, I would have to assume there is a pocket of air somewhere.
What method are you using to bleed; 2-man, gravity, or power?
Before you go crazy, answer this; Can you get a hydraulic resistance with 3 or 4 quick full travel stabs on the pedal and pressing down on the last?(remove the floormat.) If yes, that says the M/C is working, and you may have a mechanical issue. If no, then the problem is most likely hydraulic/air.

The method of pushing the pistons back is neat, and I have used it myself on occasion. There is a bit of science behind it tho. The idea is that forcing the piston back, will force trapped air somewhere upstream,to return to the M/C. The trick is to have the piston out quite far before you start, say 80% of it's travel. Then a long continuous push 'til it hits bottom. Of course,the compensating port will have to be open for this to work.And it is best to allow the system to rest for a period of time, to allow the air to migrate up through the C-valve. So I usually remove the calipers and pads, and install blocks or C-clamps, sized to allow about 80% piston travel. Be careful to not allow the pistons to pop out,or the reservoir to run dry. I do both sides. Then I remove most of the fluid from the reservoir. Then I force one piston back to the bottom,and clamp it there, and recheck the reservoir. I remove more fluid as I see fit.With small reservoirs, you might have to remove fluid more than once. Then I repeat on the other side. And finally top up the reservoir. Then I walk away for a few hours, perhaps overnight.
During the away-time, the air can continue to rise up into the M/C.
The next morning, I have a helper tickle the pedal, while I watch the compensating port for the emergence of the final remnants of air. Tickling the pedal is just that; very short gentle strokes. Just enough stroke to compress the air tiny bit. Then release the pedal to allow the air to pop up into the reservoir.As the air pops out, fluid will flow into the chamber, repeat as often as necessary, until no more air pops out.
For this to work, the C-port has to be the high point. If this is not possible, then the air will pile up at the other end of the piston chamber, and all the tickling in the world won't help. In this case I crack the fitting at the M/C and allow the air out there, while the helper maintains a bit of pedal pressure. As soon as she stops farting, I secure the fitting. Then it's time to put the calipers back on and retest. And then we move to the back,if so required.
Of course all this dinking around means the possibility of brake fluid going everywhere, so protect your paint.