I "rebuilt" a set of the rear "dutch door" hinges (1/2 doors pre-'75 40 Series had.) I drilled-out the old pressed-in pivot bolts and used Grade 8 (because they are shiny, and corrosion-resistent!) bolts as replacements, with NyLocks to hold 'em in place. Works just fine!
That's basically what I did with my hood hinges, except I used stainless. However, there is less room to work with on the amby hinges: the bolts for holding them to the tub would get in the way of any bolt used for the hinge pin. After looking at them today I think it could work it out by separating the hinge, bolting one half to the body, then putting in the bolt for the hinge pin last.
That being said--what would I do for bushings?? The problem with mine is the bushings are gone, so I have metal on metal and they are rusting making lovely brown rivers down the back of my truck.