I bought my set of poly body mounts for my 62 4x4 from Classic Parts for like 60 bucks. My new cab isn't quite ready to go on the frame yet but I've just set them in place on my old cab that's still on the truck and they look like the will work just fine. The only thing is you will need to buy longer bolts to work for the 60-62 mounts.
http://www.classicparts.com/
For the springs, the 73-87 springs should work for the back but not on the front. My 62 springs are 2.5" wide but taper down to 2" at the eyes/mounts. The 73-87 springs are 2.5" all the way around. If you want to run the 73-87 springs in the front you will have to either buy or make a new set of hangers and shackles/hangers. My plan is to build new front hangers and shackles for the front and replace the stock 44" springs with the stock 52"s that are in the back. For the back I plan on doing a shackle flip and using 56" springs from the back of an 80s 2wd. I'm hoping that this will give me somewhere around 4-6 inches of lift and should ride better than just getting the springs re-arched. But I've only seen this done on the 73-87 trucks so I don't know for sure. Here is a couple of links to some info that might help you out.
http://littlekeylime.com/MrN/mrnimages/leaf_springs.png
http://www.generalspringkc.com/default.asp
Hope this helps!