actually a larger wheel cylinder on the rear will have less braking affect as more fluid required to move the pistons inside the wheel cylinder.....Just Sayin
It will take more pedal travel, you are correct in that respect, but larger wheel cylinders on the rear will apply greater force to the shoes which will make the problem worse. Its well known that smaller wheel cylinders apply less force on the shoes.
A smaller bore master cylinder however applies greater pressure.
And these brakes are crap as they come from the factory. You have to start with smaller 7/8" rear wheel cylinders, 15/16" master cylinder, and proportioning valve. Then make sure everything is in tip top shape. Then you might be able to slow the car down without the rear wheel skid.
I've been messing around with mine since '79. Back then the car was all original in good shape and it was an absolute death trap.