Rear brake line size question

[GeoffP]

I am about to install a full Wilwood 4 wheel disc conversion on my 68 Camaro that previously had 4 wheel drums (common swap I think). It was suggestion to me by Frank at Prodigy Customs to use 3/16" line. So, I bought the line the other day and while checking to make sure I had all the fittings I need, I noticed the body end of the rear brake line has a larger fitting. It looks to be the same size as what's originally on the car. Since the car has always had working brakes, has never set un-used more than a few months at a time, I am contemplating not running new line except where I have to and just returning what I don't use. I would like to hear some opinions on this, positive or negative. Also, please share your opinions on what size line to run to the rear axle. Should I use 3/16's everywhere and just adapt that one fitting or do something else. Frank, I would love to hear your opinion as well (if you read this). I just want to make sure I do it right the first time - I HATE having to redo stuff from having cut corners the first time around.