Change the oil (if the oil has been in the engine for 15 years)!

Personally, I would get it to fire up first->worry about the brakes later.
-Change the oil! (put a little of the oil in each of the carb piston reservoir)
-Fill up the rest of the fluid in the car (i.e. anti-freeze, brake fluid (even if not functioning), tranny, rearend, etc ->worry about greasing the body until later)
-Get a battery (check to see if all the lights/electrical stuff works (crank the engine over until the oil light goes off, would also check to see if the coil is firing)->I would also get a 6volt battery charger.
-Unhook the fuel line from the fuel pump to the gas tank (Later I would remove the gas tank, and clean it up).
-Spray a starter fluid into each carb (with the air filters off)->have a fire extinguisher on hand.
-Crank the car over to see if it fires up (a timing light would be good to have around too->might be hard to find a 6volt timing light)

If it does fire up, go get 10 feet of low pressure fuel line (cheap, like $0.50 a foot), a gallon of gasoline (make sure the area is well ventilated), connect the fuel line to inlet side of the fuel pump (with a hose clamp) and the other end to the gas can, and spray some starter fluid in the carb and fire it up ->repeat until spraying and starting until it running on it's own.

If you can get it running on it's own, deal with the checking out the gas tank. If you can get it to fire up with starter fluid, but not with the gas can hooked up to the fuel pump, the carbs may need to be cleaned up or the fuel pump needs to be replaced/cleaned up (but your fuel pump has a glass dome, so you should be able to see if it is pumping fuel).

Or, do it right:

-Pull/clean gas tank
-Change/check fluids
-Pull/clean/rebuild carbs
-Check (inspect for wear or cracking)/clean (blowing the lines clean with compressed air)/replace fuel lines
-Reassemble/hook up battery, check electrical system out (check lights and stuff, and crank the engine over a couple of times)
-> Inspect/rebuild brake system.
-Add gas to gas tank, and crank

That's my 2 cents worth!

Paul