BUT- lets back up.
Did you only change that steel line? nothing else? Why did you change it?
IF that is the only thing you did, you are just messing your self up checking these other things. IF the brakes worked fine before and you only changed that line you need to be checking things down stream to see if something couldn't handle the change before you start messing up stream again.
He did change the master cylinder, even if he had the original one in place rebuilt, you still need to check the air gap between the master and booster regardless
