1970 C20 axle swap?

[Hittman]

Hey guys, this is my first time posting so bear with me. I recently bought this C20 from what I understand to be the 3rd owner. This is my first of this generation (I've had a few '73-'87's) and by far this is my favorite body style. The clock shows only 56K and I believe it to be true as it was an Iowa farm truck and shows very little rust. The body is super clean with only a couple pin holes coming through the rockers. The cab floors are prestine and cab corners look great too. Not bad for this area of the country! It does have a few bumps and scratches (mostly on the box - the tailgate is shot) but completely un-molested - original orange with white top and even the factory pin strip. It is a very low option beast with 350 4bbl, 4 speed, heavy duty springs - oh yeah and that pinstripe - that's it according to the VIN. No power steering or brakes. I have yet to decipher the rear end but it is definately geared pretty low. She runs like a top for a 37 year old motor.
My main questions to you fellas is how hard is it to swap axles/spindles from a half ton? I don't particularly care for the stock 16" 8-bolt rims and am somewhat limited on wheel choices. I now have a set of the factory cheap chrome rims from a 2001 3/4 ton which will improve it's appearance immensly but I much prefer the stock ralleye wheels with the right tire. My brother has a '72 parts truck with 5-bolt ralleyes. Am I correct that '72 was the first year for the 5-bolts? Regardless, I am considering the swap if I find it isn't too difficult. What things do I need to be aware of? It's got to be easier than an entire body/frame swap right? This could also make it easier for a disc brake swap too I assume? I would think the gearing would be a little higher as well in a half ton.
Ultimately I would love to have a nicely optioned SWB truck. For the time being however I thought I would play with this one for awhile since it is such a solid truck that needs very little. I am on a tight budget but would like to add some nicer features like power steering at least and I would like to trim it out like a Custom or even an CST. Anyone out there have any trim they would like to part with? I prefer '69 and up trim. I am located in the NW part of Missouri. Classic Industries and LMC have much to offer but it could cost a fortune to buy all new trim. If you guys know of any other resources I would be much obliged. I am pretty wet behind the ears when it comes to this generation truck.
Thanks in advance for your help. There appears to be a lot of valuable information available on this sight!