I’m gonna muddy the waters a bit more. With 35’s & 4.11’s I would reconsider the 5speed in general. UNLESSS you are planning on a lot interstate driving- in which case I have no experience. If not, the 5.3 has no trouble keeping up with traffic with 1:1 final drive. I have no problem getting to and holding 60-65. 70-80 is totally with in range, but I imagine the gas consumption would plummet.
If anything I’d like one more gear between 1st and 3rd. 2nd is to low on the pass (10% grade) and 3rd is to high, so I rev up the hill in second.
If you’re set on the H55, then proceed. Seems like the desirable NV4500 trannies are getting expensive, but they are robust. I personally would have little use for fifth. I suppose if I had it, I’d use it…