Help Diagnosing brake problem

[smh292]

I have a 1971 LWB with manual brakes, discs up front and coils and drums in the rear. About a week ago I was driving and the pedal felt mushy. I opened the master cylinder and it was bone dry. I added some fluid to hopefully see where the leak is, and I cound not find it. I know I should bleed the lines and I plan on doing it this weekend, but while I was looking for leaks I looked up under the dash and the boot for the pushrod is shot and it looks like a little bit of fluid is coming into the cab.

That being said, I think the MC is bad and needs to be replaced, which is ok since i have a brake booster I plan to install so now I can get a new MC that is for power brakes. I believe the proportioning valve does not need to be swapped out.

I also plan to install new drums and shoes in the rear and rotors and pads up front.

What is still bothering me is why the MC was bone dry yet I can't see any leaks anywhere where that much fluid would go.

Any suggestions? Also, I'm wondering what order I should do all the replacement parts? Thanks for the help.