I can see em all now.
Looks like things are coming along pretty good. I can see that rust converter stuff would work pretty good for you. Just hit the whole thing with the grinder and a good wire wheel cup on the grinder and it should be pretty good. Then hit the whole thing with the rust converter and you will have a good solid rust free base to paint and finish. Least thats pretty much how I did it with my last frame (only had it sandblasted first) and axles and such.
Few other products you may find handy in fixing up the old truck.
Rust encapsulator is good for those pesky spots that you can't fully grind off and might be worried about, or tight spots you can't get at to remove anything more than the loose scaly rust.
Pre cleaner/degreaser I was shocked how well this stuff worked, cleaned up all the grease and made the rubberized undercoating on my fuel tanks come right off and works great to prep bare metal for primer and paint. Last one, your fuel tank looks pretty good but a bit of rust under the straps and such not nearly as bad as mine, but this works great and its a pretty simply project.
Tank Tone works great on refinishing the fuel tanks, makes em look like new and gives em many more years of rust protection. I used it on my tanks about 3 years back and they look just as good as when I first did them, just a little dirtier.
Before:
After:
Your truck sure has come a loooooong ways, looking good. Your gonna have to take it to some shows when ya get the drop on it. Your making me want to get back to working on my other truck and finish it up as good as yours.