If I where going to do it, (and I haven't) I would make sure the shackles mounted in the opposite direction as normal!!
For instence, in this pic the shackles will become straight under load, and you will lose the ability to spring! They should point forward in this application!!
Just a Thought!!
Another thought related to this one... You would also have to completely disassemble the leaf spring packs and reverse the order of the leaves, stacking them
inside the arch of the leaf spring. If you don't do this, you will only have the spring action of the main leaf, essentialy acting as a monoleaf suspension.
Personally, I'd be worried about the results of a spring to axle U-bolt failure, as well. Consider that the
ENTIRE weight of the vehicle would be supported by those U-bolts, under
tension!! Sixteen thin bolts, Grade 8 or not, seems like VERY LITTLE keeping your vehicle from hitting the pavement.
If the spring fails, the chassis won't come down and hit the axle, WHOOPS! It just dug into the road.... Probably wouldn't be a whole lot of fun @ 60-70 MPH...
Just a few things to consider for safety's sake.
If you're gonna run full fenders, I'd seriously consider the later model chassis swap, either S-10 or Dakota. There are several build threads, some time browsing the "Builds" section would be well invested.
Regards,
Shea