I would reconsider. This tire/wheel combo is close to 200# a piece. Tire choices are limited in the 16.5 category and quality surplus are getting harder to find and more expensive when you do.
The Craig's ad you listed: Those prices are high. The 12 jolts can be had for around $50 a pop, sometimes cheaper. The 24 bolts I'm not so sure about but I don't recall them being $95.
The 12 bolts are rated at 3850# as I recall, as are the bulk of the surplus tires available. I would imagine this would seriously impact the load capabilities of your 450. The 24 bolts come in 2 flavors if I understand it correctly. One is rated at 3850 and the other 4250 (I believe). The later will be more in line with your 450s' load capacities, as long as you get the e-rated rubber to go along with them.
I'd evaluate your usage. If you don't intend to tow a load I run E-rated singles, but if you do intend to tow I'd probably stick with the duality config, which rules out the surplus route, and is also going to impact your practical tire choices. The taller the tire, the harder it is to find them in a narrower dually friendly configuration.
I've done 75 in my van, with no major issues but.... they're 37" surplus heavy as snot tires on heavy as snot re entered rims that may or may not be all that true AND this rig is running around 10,500# on a good day. Why on earth you'd want to blast something like this down the road at 85+ mph is puzzling. It's like a building on wheels, and jacking it up on 37s with 8" of lift doesn't help in the handling dept.
At 65 I'm pretty comfortable. At 75 it feels ok but I'm starting to question stopping capability and maneuvering in an emergency, and 85 is somewhere I'd have little interest in finding myself.