Brakes Unions: Confused

[Fourcandles]

Hi All,

Wondered if anyone can help?

Bought a part built roadster last year and am now trying to figure out the brakes. So far I have:

Sierra Master cylinder fitted and looks ok

Brake lines where already fitted when bough it.

Flexi's in and attached at Caliper end.

I roughly know what we need for the Unions i.e Male, female, T piece, Brake Switch.

But am confused as hell about what size unions we need as they appear to come in various sizes and not sure on size of brake lines.

I have also read that I will need metric for the flexis but UNF for the master cylinder?

Any advice greatly appreciated.

Also any ideas which flaring tool is best when the lines have lready been fitted.

Ta.