Scott, I've been having the same problem. I put a post under the body section of the web site. I'm about to change the master cylinder. I don't think I'm getting too much pressure to the rear, as they don't lock up till I'm pushing pretty hard on the pedal. I think i'm not getting enough pressure to the front, so i'm going to replace the master. I have to start someware and that is my best guess. I've got manual brakes, but they should still stop better than they do.I was told there was a tech service bulletin out during the 80s on that, but I can't find any info on it.
John