[HWYSTR455]

3/16" brass compression fittings 'work', but are not recommended for brake lines.

But I've done it before in a pinch.

A good flaring tool will do inverted flares. But you will have mixed results with 'used' steel line.

You can do a regular flare and use a brass union, that's totally acceptable and lasts.

If you are going to metric calipers, there are unions that are standard flare on one side and inverted on the other.



.