Decided to drain fluids first before attempting to start it up again. The fuel came out almost as green as the antifreeze - though Dad thinks that could be from an additive (for winter storage?). Glad for the Stovebolt forums on petcocks. Oil was black as black can be and when I asked Dad about this he said he used recycled oil in the truck. He did his own oil changes on his other vehicles and changed oil frequently enough he thought it had a little more life left in it. Antifreeze looked good.
I found the brake line culprit. Along with the truck I inherited a flaring tool. (this seems as oddly doomed as getting a patch kit with an air mattress). Hope I don't have to use it too often. The worst part of the line was as it ran under a frame brace. I suppose salt and gravel stayed lodged in that area and ate away at the lines. Interesting to see a cross section of the line and how it appeared tear-drop shaped inside. Not sure if that's from the way I cut it, or material wearing / deposits inside the line.
Brake line replaced, son helped bleed the lines (except for one rusted bleeder valve... well they ALL were rusted but this one needs more time) and the pedal doesn't go to the floor anymore. Still a bit soft yet so that other line will need more attention.