1973 Dart brake failiure

Yes, I have four drums, if that's a disc MC than I have no idea how it got there.

I do plan on replacing or repairing the MC, but I'd like the vehicle to be operable atleast every now and then so I'll probably try to refill it tomorrow and see if it holds at all.

And yeah, when the brakes went away I was driving, luckily only about 15, and luckily on a flat road.

Goes without saying im not looking to temporarily fix this problem, but if I do get a replacement it will take weeks to ship out here.