You have a few options there. You can go leaf spring really really really easy.
http://offroaddesign.com/catalog/88-...Conversion.htm
Or you can setup a 4 link like the dodge has just as easy.
http://offroaddesign.com/catalog/Fro...Conversion.htm
Going this route will be far less work than trying to make the dodge frame work. And the end result will be much cleaner.
Your most economical route will be to go leaf springs and to find a Dana 60 for a leaf spring truck. You will be able to sell the one you have for 700-800 bucks, there are plenty of jeep guys looking for that axle to cut down and stuff in their jeeps.
You should be able to get the leaf spring Dana 60 for similar money.
with this the only custom fab you are going to have is cutting the coil spring buckets off of your frame and plating the frame back in. This is going to be much less work than trying to make that dodge frame fit a Chevy cab.
I want to add that I have had a good deal of experience with this sort of thing, I have been building trucks the last 15 years. For instance look at my 72 K30, it started life as a C30
I built all the pieces myself to convert it to a 4x4.
This setup worked out really slick. (It has a 12 valve between the fenders here)
As well I have turned this:
Into this.
Building a very capable leaf spring suspension is not hard at all, your truck built up with a good sway bar front and rear should be plenty stable for on road cruising, if you put the disconnects on it you will be able to get out and flex it.