When I did my disc brake conversion I decided to do my own lines rather than use the pre-made that came with the kit. The ones in the kit where way longer than needed and were a mix of rubberflex and solid.
If had to do it all over again I would have just stuck with the stock kit. Half the double flair kits are pure junk. I went through three of them, then there is the brake lines, the stock steel lines you get from the auto parts store are impossible to bend and flare properly. Spend the extra money and get the premium nickle/copper lines, they are easy to flare, easy to bend and resist corrosion.
Good luck.
Ron W.