Brake question
 

I have a brake issue with my 1972 C20. Truck has power brakes, disc front and drum rear. All stock type components.
The pedal seems to have the appropriate amount of travel though it is a bit soft. The weird part(at least to me) is, when the engine died(vapor lock) I had absolutely no brakes at all. I know the brakes have been worked on at some point in the last year or so.
I am questioning if the brakes were just improperly bled? Or is something else a more likely culprit?