I've done the springs and body insulators on my 65, and the combination of both greatly improved the ride quality.
For the springs, I went with custom 4 inch lift springs from alcan. The hardest part of doing the springs is getting the old bushings and sleeves out. There are many threads on this, but I used a combination of propane to melt the old bushings and then an air hammer to get the old sleeves out. I've read where some people have used a ball joint removal/installation tool to remove the old sleeves, but I didn't have one of those available.
There are 9 body insulators. As Mike said, there is a rectangular one under the radiator that is by far the most difficult one to replace. There are 2 more right under the front floor pans, 2 more near the gas tanks and 4 across the back of the Scout. I used a large floor jack and various lengths of 2x8's to lift the body high enough to replace each insulator. The problem with the one under the radiator is that there is a bolt that is welded on the bottom of the radiator support. That bolt then goes through the insulator and then the frame and is nutted on the other end. You've got to lift the front of the body high enough to get that bolt to come out of the frame and old insulator. If I remember correctly, I had to lift it about 6 to 8 inches to get the new one in.
The other insulators are easier because you remove the bolts and nuts holding everything together before you replace the insulator. As Mike said, you'll need new hardware for these as your existing ones will likely be un-usable once you get them out. I think I had to take a sawzall to a couple of them. That said, the hardware that came with mine were incorrect for my application (note that I did not purchase this kit from IH Parts America), and I had to go to my local hardware store to get the correct length bolts
I did the insulators in one full day if I remember correctly. The springs probably took 2 days because getting those old sleeves out was extremely time consuming.
Would I do it again? Heck yeah cause as I mentioned, the ride quality improved greatly.