68 4x4 suburban suspension/disc brake questions

[hifiguy]

I'm currently looking at buying a 68 4x4 suburban that has a 4 inch lift and has a 79 chevy front axle installed. I think the 67-68's normally had drum brakes in the front so I assume that the reason they swapped in a 79 front axle was to gain disc brakes. Now my question is this: while looking the truck over I noticed that the left side rear shackles were bent out about an inch or two. After looking more closely I noticed a crack in one of the shackles aroung the upper bolt hole. To me it looks as if the spring perches on the 79 front axle don't line up exactly where the OEM 68 leafs sit, and because whoever did the swap didn't take the time to relocate the drivers side spring perch, they had to bend the shackles out to accommodate the new spring location that is now determined by where the spring perches reside on a stock 79 front axle. Does this seem like a correct diagnosis of the problem, or am I way off base? Can a 79 front axle be swapped into a 68 with no problems? If not what should be done? Is it a common swap? Any info would be greatly appreciated as I'm new to the 4x4 versions of the 67-72's