http://www.performanceplustire.com/p...zeShort=900-16
Above link is to performance plus tire, who offer free shipping in the US. If you can find a place near the border that accepts UPS deliveries, this is one option to get you fresh and original tires. They charge about $20 over the list price, but that is more than offset by their free shipping.
Towards the end of service, the DND started to provide us with commercial pattern tires for installation on the 3/4 tons. We even had Michelin radials near the very end. While the original tires had that "for 5° rims" on them, the later tires did not, and we had no problems with them. You should be able to use just about any commercial 16" tire, although you will have to come up with radial use valve on center inner tubes, and re-use the old flaps. Of course, you could likely get away with the regular inner tubes as well.
We have a set of the modern LSVW Michelin tires installed on the 3/4 ton M37 at the RCA museum here in Shilo. No problems with them, although they kind of give it that dune buggy look.
Of course, you must use extreme caution when inflating the split rim tires the first time, or anytime that the pressure has gone quite low. Those rings can fly off without notice during inflation, and will kill. You can wrap chains through the rim and around the tire, or inflate it underneath a vehicle, and use a remote filler hose/chuck.