Now that you cut the drums the shoes have to move out farther then they did before. Are the drums still in spec or are they too big now and the shoes cannot make up the difference with the slight movement they have.
The brake cylinders should easily push the shoes out the extra distance, unless they skimmed way too much off the drums. New shoes and a firm pedal after bleeding would indicate you have everything right. The remaining suspect is the drums.
I had this problem on a car. Brand new drums, cylinders and shoes and the car failed the annual NCT road test. Someone suggested I drive a few miles with the handbrake partly on to bed the shoes to the drums. I did and it worked, the car passed the NCT a few days later.
Try riding with your foot lightly on the brake pedal for a few miles and see if it works