Now the fun begins!!!
I think that you should be able to move plenty of stuff in a hollowed out bus. And owning something at the end of the trip will sure beat watching someone else's rig drive off with a sack of your money in it.
The 4.33 rear will only get her to about 60, but hey, it's a bus. I have a local truck shop looking into a higher rear for her, but I don't think I'm going to like what they have to say.
Strictly speaking, what you are looking for is a lower
rear end ratio. A higher one will make you go slower. But I know what you mean, as I have a 6.5:1 rear end, and I can only make 50MPH on a flat with a tailwind. I want a 4.33 rear end so I can get up to 67 (theoretical) top end.
What size engine do you have? It may be that the engine just doesn't have the capability to push the vehicle faster than 60. Or it could be the transmission set-up. What kind of tranny?
If you want some free moving pads for packing, take the vinyl off the backs of your seats. It won't be thick padding, but it will be good for keeping things from chafing. The seat upholstery will work the same way, but you end up with smaller pieces (which is not necessarily bad).
Congratulations on your purchase! I bet the maintenance was pretty decent on a military bus, and that makes all the difference in the longevity of the vehicle.