A few months back my attention came back around to the truck. As much as I like the 327 in the 68 this will be a working truck and the 366 from the 89 is a better option. Plus it already has all of the accessories like power steering/hydroboost pump ans A/C compressor already mounted. Further measuring looks like the hydroboost will bolt up to the 68. That front axle thing is killing me so I get to looking at the SPIDs on both trucks, they both have an F050 (5000lb) front axle, it is just that the 89 is 6 inches too wide. More measuring and it looks like the 89 spindles might fit the 68 axle. I researched on the internet and found this:
http://www.stemco.com/f/qbin/STEMCO_Kaiser_2013.pdf
I found that the bore in the older axle needed to be enlarged by .0070 and I could put the 89 spindles on the 68 axle. That was the deciding factor, I'd just go ahead and use the entire 89 frame and drivetrain in the 68 but with a narrower axle.
Rather than pull apart the 68, I pulled the front axle from the 70 GMC frame that I had acquired and took it to a local machine shop to have it bored out. I also ordered a set of kingpins online. This was December 2015. After a few weeks of waiting to get that axle back I pulled the 89 in the shop and removed the brakes, spindles and axle. Things got held up at the machine shop and I finally got the 70 front axle back in early March 2016. I cleaned it up, repainted it and reinstalled the 70 axle in the 89 truck with the 89 spindles. It went smooth except that the stops on the steering linkage did not line up with the stops on the axle so I had to drill and tap a new hole.
Here are pictures of the axle installed with the spindle on, the stop bolt missing the stop, the new hole drilled and tapped in the linkage and then the linkage installed with the bolt in the new position hitting the stop.