Very cool. I've seen a few of those converted to campers in the Scuba world. Seems to be a popular low budget base. The square walls make for easier converting than a van, plus offer some additional space. Depending on the builder they are usually very stout, albeight heavy.
I think the whole build plan overall is a good one, with one question. Why swap out the Dana 80 for a much weaker 10.5?