Hi John
Can you post a picture of the style of cage nuts you are looking for sizes and number of each you need.
Many of the different sizes and styles are available from different sources, often the problem is finding a source that will sell you a few. On my web site I mention caged nuts and as a result I keep getting e-mails from fabricators in China who want to make them, wonder if you could con them into making you 25 prototypes so you could check them for fit? I'll save the next e-mail that wants to produce sheet metal parts.
The smaller sizes up to 1/2" are relatively easy to find example
MAC's Antique Auto Parts if you need more than 50-100 MAC's will general give you a discount.
There have also been several other restoration threads on the topic of Caged Nuts that have listed various sources you might want to check out.
For a few really large ones, if they are the folded sheet metal type you may have to find a shop with a CNC plasma cutter and have them cut out the right steel. I have made ones and twos just doing a drawing then cutting and bending the steel by hand but it takes forever, you have to make 5-10 before you figure out how to do it to get the quality you want.
Cheers