ok dude

First things first, when bleedin brake start the furthest away from the servo, and work backwards. Now there are four nipples, rear left, the p valve near the rear right which has no nipple just a through and through pipe, front left, front right.

Now I am assuming that you have had the rear wheels of to check the amount of lining there is left on the rear shoes as if they are worn to excess then that is why you have excessive travel in the brake system

So if there are no leaks at the servo check around the inner rear wheels look for dampness that indicates one or both of the rear wheel cylinders are kaput

If all looks good then the problem lies with one of three things A, the servo, B the master cylinder, C the one way valve between the servo and the manifold;

To test

With engine on pump brakes does the pedal get harder?

A, servo , with the engine off push hard on the brake pedal, start engine leaving your foot on the brake pedal, you should feel the pedal pull or fall away from you, making your foot travel further. If it does this its ok. Get someone to listen in the engine bay for any whistles or sounds of air escaping.

B master cylinder, ok this ones a pain, best you can do is see if there is any fluid leaking from it. You can test the master cylinder yourself but this is best left to someone with the correct equipment

C, one way valve, connect to the servo is a pipe which provides an air supply to boost the brake pedal, this should pull out of its housing, it should be FB tight and should let out a hiss when you pull it off, the other end should be connected to the inlet manifold in a petrol or pump in a diesel, with the engine running you should feel air coming through the pipe. Next step remove pipe, blow through it you should only feel air going towards the servo, if you get air flow the other way then the valve is duff

And last thing don’t throw the float away your low level brake fluid light (same system as handbrake warning light) wont work