I'm in the process of writing a tech tip on this very same swap. You can bolt the crossmember from '71-87 into your truck; I used a '75. If you can find one, a '71 or '72 is preferrable, because you can use the rearend as well meaning you would have 5 lugs all around. After '72 the rears went to leaf springs, and you would have to cut off all the brackets from the rearend and weld the '65 brackets on. Not impossible, but if it can be avoided, all the better.
As Bear63 stated, you can swap out just the spindles, but the locations of the control arms from drums to disc is different on the crossmember. This means if you just swap out the spindles, you will have to remove all the shims from the upper control arms for the camber adjustment; it's still not enough to get them right, but it will work.
I know it's late, but hope it helps.
