I have done a couple of bolt on EFI setups. They are easy. FITech makes a kit for about a grand that includes everything.
If its gonna be a daily driver rather than something to tinker around in once in a while, consider doing an LS swap. Putting a modern engine and trans in a truck like that is simple. You can find 5.3L engine/trans setups with computer and all rotating accessories for cheap with plenty of miles left. And there are no shortage of kits that include motor mounts and everything you need to retrofit it into the old truck.
I like the squarebody GM trucks like yours from 73-87. Certainly a lot better than the next generation which to me look all plasticy. Donk is right about the late 60s trucks up through 72...great looking vehicle and will probably be my next project after I finish this damn RV.
Here's a few pics of my 75 K20 before it went under the knife. And after.