Many thanks to all who replied. It turns out that one of you were right--the back of the reservoir was empty. So, I filled it to the neck, and used the coke-bottle method of bleeding (didn't need a second person). No leaks, and the brakes are good!

I did notice that the two front brake lines were new, so the PO must have had them replaced, and either he or his mechanic was fooled by the rear reservoir compartment when it came time for bleeding.

It's the first time I've done this, and it seems I was needlessly worried. Many thanks again for your guidance.

J. S. Park