I'm not sure what I'd call that orange. When it's new, it's pretty bright, just a little south of international orange. The desert sun fades the paint pretty fast so I think something like reefer orange would be about right for an engine that has been in service for a while.
Modeling NN freight cars is easy - they only had one type, at least of the conventional variety. They had about six hundred wood and steel composite ore cars that were hauled by pit locomotives to the assembly yard at Copper Flat. There, the heavier power hauled the ore to McGill concentrator, where the ore was turned into blister copper. Even though the mill concentrated 20,000 tons a day, a very small amount of blister copper was produced from each ton of ore. Only three trains a week made the trip from McGill Jct. to Cobre, where the blister copper was sent on to Utah for smelting.
The blister copper was carried in high side 50 foot gondolas. I think the NN had about 45 of these and they were the only interchange freight cars they ever owned. The ones I saw in the late 70's were oxide red and had reporting marks of NN and the car number and data. There was one NN caboose and it was a standard International Car Company wide vision variety painted blue with a yellow roof. Again, just NN reporting marks and data, nothing fancy. That was it. The railroad had a few wood boxcars in the yard that were used in work train service along with a pretty decrepit outside braced caboose. There were a few old single dome tank cars that were used to store heating oil for the concentrator. When the NN was still a going concern, that was about it. The cars you see at the museum now have all been bought from other roads and repainted in NN colors. Almost all the traffic on the NN was inbound and was carried by interchange cars from other roads, It was usual to see five gondolas of blister copper lead by the SD-7 and the RSD-4 heading out to Cobre and a train of 25-30 cars on the return trip with diesel fuel, mixed freight, and machinery parts. All these cars were from foreign roads and could be from just about any railroad in the US, the UP, SP, and WP predominating. It was a neat operation to railfan, much like the Trona in California. Alas, they are both gone in terms of independent operating railroads.
I hope I haven't given you more information than you really wanted to know but the NN is a great railroad to model so I'm glad to see someone else interested in it.