Re: How to remove rear hard brake line
The picture of the kit you are installing shows what appears to be a combination valve that was discussed in the article to which I provided the link above. The article indicates the combination valve provides "all of the separate distribution/valving functions described above (distribution block and warning switch, metering/hold-off, and rear proportioning) were integrated in later second-generation disc/drum cars into what became known as the "combination valve". So, all you should need is the 10# residual pressure valve as John noted above (Wilwood has a nice one).
'69 Z/28, Lemans Blue/White Stripes, DZ302, Tremec Magnum, 4.10, Procar Elite Seats,
Custom Upholstery, Dynatech headers, 17" VWW V45's, 235/45, 275/40, C5 Front Brakes