I just did the same thing on a 70 model truck using a 2002 hydroboost setup. I don't remember the size, but I got 2 premade lines at Oreilly's with the ends already on them and just bent them to the shape I needed.
Just go the the store and have them pull a master cylinder like you are using off the shelf and then go match it to the lines or fittings they have.

They aren't metric or anything weird, as you can see since one of your lines fits.