!980 Range Rover - problem bleeding brakes...

Hi everyone,
I have a 1980 Range Rover that I am slowly rebuilding. I replaced all of the discs, calipers, pads (and all the suspension) along with all of the brake pipes within the visible area of each wheel.
When I came to bleed the brakes, I tried all the bleed nipples but found nothing I did would push the fluid through.
Is there something specific on these models I don't know in order to bleed the brakes?
Many thanks for any advice.

get a easyblead what attaches to your tyre valve/master cylinder to force it through the system

Release pedal slap master cylinder press pedal and repeat so on.

Also valve on rear brake system eg earlier defender play up