Trouble bleeding brakes

[Jemo]

I initially bled my MC off the truck and brakes, got all the air out and while driving it onto a trailer this week realized the brake pedal almost goes to the floor and doesn't stop very well. It's a frame mounted MC/booster. I jacked up the rear end and measured 21" from the bleeding valve to the ground and measured the distance from the top of the MC to the ground, it's around 19".

I'm going to bleed again. Is this enough of a difference? Any other tips?

Jeff