jmc...I'm going through the same situation right now. More PSA's are a waste of time at this point.
You need to get your dad to a local RO, experienced in prostate cancer immediately. He can beat this thing but immediate intervention is required. Salvage IMGT plus hormones, starting ASAP.
I've made the trip to JHMI serveral times, and as Tall Allen says, they are surgery experts, but not "top dog" radiologists, which is what your dad requires.
Best of luck and keep us posted.