Wondering about the absence of the inners too. If it stays in my allowable price range, I will ask more questions.
First thing to change would be the rear axle. Wow, 5.14...I guess they need that for heavy loads in the mountains. I'm surprised to see it has coils on a C20, but maybe I'm too used to seeing K20s with leafs.
10 years ago, I brought a 2 1/2 ton flatbed out of Pagosa Springs that had no rust on it too. Amazingly solid cab. Hauled it home on an 18ft trailer with my 2000 K10 Silverado. The bed stuck out over the back of the trailer by 2 ft...