Does sound like a cool idea, did you ever get it done, I have several boxes out in my pasture that I have not even looked at in about ten years don't know if any are still good, I do wonder why take the box off of the most capable off road vehicle in the world and stick it on a M35? BTW they are heavy and well insulated...
I used to import 404s back in the 90s, but only have one left with a 5 cyl. turbo diesel conversion and a radio box and a drop side box, I competed with one in the 1995 Four Wheeler "Top Truck" competition, would have placed much higher if I had not listened to my spotter but that is another story..