Another tidbit from my brake upgrade on my 57 3100. I'm using a 67-69 C10 master cylinder which has a 5/16 outlet for the front brakes. I'm using 1/4 hard line for the front so I needed an adapter. No problem, I picked up an Edelmann 258450. Only to discover that the threads bottomed out just about the same time the flare seated. I couldn't tell if the flare was tight enough to avoid a leak. I checked an AGS BLF-19 adapter an it's a full 1/8" longer in the threaded part. Fits much better.
Here's a pic.

Who knew?
I'd be much further along on this project if I did'nt spend so much time learning stuff.

regards,
Leon