Brake help please, running out of options

1983 D90. Have an issue requiring me to pump the brake pedal (a LOT) to get any grab. I have replaced AND adjusted the rear cylinders, replaced the front calipers and rotors, replaced the master cylinder, and FULLY bled the system. I have done the basic servo test - engine off, pedal pumped to hard, engine on, drop to floor. All good. I have checked the vacuum pump, and it's making suction.
Still have to pump for any grab. It's snowy here, so I can lean out my window and see that both the front and rear WILL lock up after multiple pumps.
What am I missing???

Well, having replaced all the calipers, master and slave cylinders etc, at least you know what it isn't.

I replaced the clutch master/slave cylinders on my Defender TD5 and could not get pressure in the pedal whatever l did.
I tried bleeding both ways, using my pressure bleeder, doing it manually, etc but it just would not work.

As a last resort l wedged the clutch pedal down with a piece of wood and went to bed. Next morning it was fine, and has been ever since.

Jack her rear end up and re-adjust the shoes ... you did fit them the right way round, didn't you?

When the cylinders were replaced, the bleed nipples are at the top, aren't they?

Lock up the wheel on the adjuster, and back off a couple of clicks, then do the other one.

You did fit the new calipers on the correct sides, didn't you? The bleed nipples should be at the top.

If you have fitted one of the components upside down, don't be embarrassed, I think that most of us have done things like that in the past

Have you checked your flexi pipes for ballooning, expanding under pressure causing the pipes to expand rather than expanding the brakes

Check the front wheel bearings .. when they get 'loose' they allow the discs to move and lose braking effect.

Hey, thanks for all the replies. I'm not quite sure about the etiquette of responding to each of you, but here goes.

@Paul D- I see what you mean, I'll give that a look. I am totally new to all this, and I replaced all the front wheel bearings when I did the rotors and calipers, so maybe I tightened them wrong and they've already gone.

@cornish rattler- Checked, looks ok.

@Oldseadog- That is the procedure I used to adjust rear brakes exactly. Are you suggesting maybe I should adjust again after all the other work and some driving, just to be sure? Also, yes, all parts fitted correctly, double-checked. And I'm just a poor American trying to set up my dream-vehicle w/ about zero knowledge about Land Rovers (much less an 83 "Defender") locally. No embarrassment here, just super appreciative of all you guys help on here. Thanks.

@lightning- So here is where I am going to really show my ignorance. Are you just using the clutch system as an analogy, or am I supposed to be bleeding the clutch system too? Is the clutch system somehow connected to the brakes? Also, if you ARE using your clutch story as an analogy, would it be helpful for me to wedge my BRAKE pedal down overnight? If so, bleed nipples open or closed?

Thanks again everyone!

go and clamp the rubber flexis one at a time (do rear one for both) and see if you can isolate which brakes are the issue.

i had an issue on mine recently where the rear snail adjusters were broken. so as much as i thought i had adjusted it correctly, when i used the brakes it pushed the linings up and off