[Barnsnake]

It sounds as if there are two things going on.

The old cylinder was likely a smaller diameter than 3/4" and thereby had more leverage. If you disassemble the old one and find that it is 3/4" or larger, then there must be some kind of mechanical binding with the new one. Pedal effort should be purely a function of cylinder sizes.

The "moving engagement point" is likely due to air in the system. A bubble in the master cylinder itself is tough to get rid of, especially if the master is near level. I would suggest raising the front of the car as high as possible and bleeding the master cylinder at the bleeder near the line connection, then lower the car and bleed the entire system again through the slave cylinder. Make sure the line from the remote reservior is not full of air and re-introducing it under certain conditions.

Keep us posted on what you find.