Brake’s won’t bleed on 87 LX

After sitting 20 years I would not trust any of the components. Get a new MC, front calipers, rear wheel cylinders and all new rubber lines. Blow out the hard lines, go through the combination valve (disassembly, clean, inspect, and reassemble), bench bleed the MC, swap everything out, and put new quality brake fluid in it. Stopping is a priority so don't go cheap here and in all honesty you can get all of this for the stock Fox brakes pretty damn cheap.

Brakes hoses do collapse too. I know that sounds odd, but it's happened twice on my work van.
Even disconnecting the hose completely from one caliper and pressing on the brake pedal didn't push out brake fluid.

Me personally, i'd start my pb blastering every brake fitting.
You are going to try and undo them and they aren't going to spin, they are going to twist the hard brake line and make your problems much worse.
Work them back and forth slowly, be patient. Once they are all done, put a compressor nozzle on each line.

Like aero said, you need a full rebuild at this point, if you don't get every piece a garbage in the lines out, it will be bad news later.

I would trust all the components and just replace what is needed
Granted it might need a new master cylinder or anything else
But it might be okay with just a good bleed and new fluid
Keep in mind that the proportioning valve (block or combi valve roughly the same thing)
Might stick during the bleed process, supposed to be self centering but sometimes they do not
If it sticks and turns on the light, I'll tell you how to try to get it to reset

This thread has some good pictures of the core support and hood latch assembly.

I'm not so sure i would replace the entire system, but if some of the lines are butched, i'd probably buy it as a kit.
Unless you know how to flare brake lines and have access to a quality flaring tool, it can be a serious headache.

I forgot which tool i have, but it's not that great, i probably get about 65% right...

I would advise
Get a new proportioning valve to start with, so you do not beat your head against the wall
Bench bleed the master cylinder first
Then let it gravity bleed
Then start the manual bleed procedure
Someday I will post pics of how to power bleed one like yours with a old MC cap
All you do is, drill a 1/16 hole thru tour MC cap and the rubber gasket
Put the cap back on, take shop air and blow lightly about 1 inch above the little hole
That will (air over hydraulic), force fluid out the lines
You can even bleed the MC that way if you get pissed enough
The 4 wheel drive Aerostar MC recall, taught us to come up with this procedure
Beat the hell out of Ford warranty flat rate after that
They paid around 2 hours to do that recall, and you could do it in 40 minutes using that modified MC cap procedure
Good luck

Just dawned on me that a 87 LX may have a metal master cylinder cap
The above power bleed procedure works with the metal caps too

A wrecking yard is where I would start
A new one might be able to be had on ebay NOS