What brake lines?

If you put the calipers in the front of the spindles you use 73 and up A-body hoses. . If you put them in the rear of the spindles you use 72 b-body hoses..

The reason the location of the calipers are installed on the rear on early applications is due to the early stabilizer bar being wider on 72 and earlier cars. The caliper will hit the stabilizer bar when turning .

If you have a narrow bar from a 73 and later car or an after market bar, Or no bar at all. install them at either location.