Not that it hasn't been done, but going to a 4 link on the rear and keeping the frontend stock, is kind of like an elevator in an outhouse.

If you want a better riding truck, you don't have to go to a 4 link.

Try swapping to different leaf spring setup in the rear.

The Ford Ranger leafs look promising.

http://www.sdtrucksprings.com/index.php?main_page=product_info&products_id=7715

When you factor in the pack thickness and arch, they are about the same height as the stock 3600 springs.

They're 10 inches longer so they should ride lots better. Plus, they are 2.5" wide vs, 2" giving them a little more stability.

They come in a few different weight ratings, so you can pick whatever meets your needs.

Here's the hangers for them
http://www.sdtrucksprings.com/hangers/ford-shackle-hanger-kits

http://www.sdtrucksprings.com/hangers/front-of-rear-ford-hangers

That's my $.02





1954 3600 Chevy Truck
"The Fake Truck"
In the Stovebolt Gallery
More pix on Photobucket