questions regarding leaf springs

[John Fabris]

I picked up a set of front/rear leaf springs from a friend.
It is possible that they are 6 inch lift leaf springs from a 67-72 truck.

Doing some research on converting my 68 3/4 ton panel to 4x4 using the fgb52 kit from diy4x.

question #1, when they say 52 inch springs, how is that measured? (spring eyebolts center to center? or lenth of spring itself including curve?)

question #2, is there a way to identify the spring lift?


Thanks!!!