Tools/Method to remove Brake Cyl And Booster
 

What do I need to take with me to remove a master cyl and booster from a 5spd '80?

My parts car is remote now, and I need to pull these next weekend.

Is the engine out yet? If not, every iteration of 13mm tool you own including swivel sockets with a 6" and 12" extension to get the mounting nuts in the footwell , a 13 mm stubby gearwrench for the lateral MC-to-booster bolt, a vice grips for the pedal rod, 11 mm flare wrench for the brake hardlines, spark plug pliers for getting the &*$^ing check valve out of its grommet.

The dash is out, engine is still in.

Seems the hard part is counterholding the bolts in the engine bay, or the two nuts for the MC?

Checkvalve = Brake Light Switch?

No, the vacuum checkvalve. Sometimes they're easy, sometimes the plastic is utterly fused to the grommet and requires additional motivation.

spray some PB blaster on the valve /rubber interface,
it will pull right out.
take some towels with you so you can catch the fluid from the MC tank,
As you will also use the same PB trick to remove the MC tank from the MC

You should also bring a crows foot for the hardlines as well. Saved my butt a few times when I redid both in my 81.

It just requires wiggling to get out. It isn't impossible with the engine in like some say, just like redoing the door locks with the door panels still on ;)