I'd try going here
TractorHouse.com | Used Tractors For Sale: John Deere, Case IH, New Holland, Kubota. first, and place a "want to buy" ad. This goes out to salvage yards, and may go to other dealers that may have some NOS parts too. Look on the left side of the page, 3rd item down in the menu. You'll have to register, and give some contact info. Put the part number, and description where it goes. Normally, anyone that may have some will contact you within 36 hours. Being this is Friday, I'd give it until next Tue. or Wed. I've found it best to not jump on the deal of first one to call. There is a possibility of getting more than several. Prices, and shipping can vary, depending on where they may be. I've received calls on parts within 45 minutes, up to approx. 36 hours.
I thought I may have found some of the adjustment screws at Steiner, but, they are the wrong diameter. It looks like yours are 7/8"-14, where these are 9/16 X 2-5/8". With that being said, the price on those are $8.99 ea. Just thought I'd add that info to save some sticker shock, if you would happen to try it, and get a call.
If by chance they would have the adjustment screws, but not the nuts, those should be easier to find. I did a quick check at McMaster-Carr, and they have more than several types. They have some Grade 8, 10 for $4.76, or on down, some extreme strength, 10 for $9.22. Here is the link for the page, at McMaster-Carr, if you want to look.
McMaster-Carr.
Another option, would be if you have a local machine shop that does piece work. Take one of your adjustment screws to them, and see if they could make what you have, out of a 7/8-14 bolt. I don't know how much clearance you have, so type of head would have to be determined, for proper clearance. Usually with a machine shop, set up time is where a lot of the cost is. Not sure how many you need, but if it's all 24, then the price each might not seem so bad, compared to the above price of $8.99 ea. If it's affordable while their set up, maybe do a couple extra sets to sell to offset the cost of yours. This is just all food for thought, if you don't find some OEM parts.
There is one more thought, and a place to call. This is a small NH dealer North of Coshocton, OH., who may just have some NOS parts laying around. Approx. 16 years ago, I found a NOS 3 sp. aux. transmission, to fit my 2000. It had been on the shelf since 1973. They took it off the inventory, but squirreled it away. It is, or was a small family business, owned by a local farmer. Really nice to deal with. Here is the name, and contact info. Bakersville Garage Inc.
59507 CR 2
Bakersville Ohio 43803
Phone: 330-897-7561
