Your '86 came with R-12 refrigerant. If your friend added 134, then I would assume the system has indeed been converted to 134.
Take a look at the thread below and review posts by Arthur Dalton. There's a bit of overlap between what you've reported and what Arthur had to say, but he does emphasize some important points that might help you get this taken care of. Don't be concerned that the car in this thread is not identical to yours.
http://www.peachparts.com/shopforum/showthread.php?t=124892