You could call these folks
https://brillman.com/
Napa does have the wire in bulk and you cut to size and add the ends with a crimper. Its really easy. Make sure you use wire core instead of carbon fiber, when using a magneto. Do a search on this site and you will find a lot on info on spark plug wires.
I bought a set of universal tractor plug wires at fleet farm and made them work.
Packard (brand) 440 wire is the old time standard for solid ignition wire.
7mm is the standard size for sparkplug wire.
Counter guys at NAPA probably aren't old enough to know what and why Solid Core Sparkplug Wire is used for!
My NAPA happens to stock it as there are still a lot of small Farms with old equipment in the area.
I'm using these;
Accel 3009 7mm S/Stk Copper Univ 90deg https://www.amazon.com/dp/B0006HJOGS/ref=cm_sw_r_cp_apa_-DNtzbPRS6J42
"I checked with the local NAPA and they don't stock anything. "
Hmmmm.... they should have some in stock. You might have to buy a roll of bulk wire. Or try another NAPA near an industrial or farming area.
This is what I am using: https://www.napaonline.com/en/p/BEL734803
It works fine.
There are other choices: https://www.napaonline.com/en/search?q=N%3D2905600%2B123253000&text=Ignition%2Bwire&isProduct=true
NAPA terminal end choices: https://www.napaonline.com/en/search?text=Spark%2Bplug%2Bwire%2Bterminals&isProduct=true&isInterchange=true&referer=search_form-allprod
NAPA terminal boot choices: https://www.napaonline.com/en/search?text=Spark%2bplug%2bwire%2bboots&q=Ntk%3DKeyword%26N%3D0%26Ntt%3DSpark%252Bplug%252Bwire%252Bboots&isProduct=true
Plug boots I am using (bulk pack): https://www.summitracing.com/parts/msd-34575/overview/
Plug terminals I am using (bulk pack): https://www.summitracing.com/parts/msd-34615/overview/
Magneto end boots I am using (bulk pack): https://www.summitracing.com/parts/msd-34525/overview/
Magneto end terminals I am using (bulk was available, can't find it now): https://www.summitracing.com/parts/msd-prd10119/overview/
Two cylinder solution >> Plug end: https://www.summitracing.com/parts/msd-3323/overview/
Magneto end: https://www.summitracing.com/parts/msd-3321/overview/ you may need to trim off some of the end of the gray boot where it bears against the magneto distributor cap (American Bosch MJK) to make it work ok.
Good luck and let us know how it turns out.
A few months ago the starting engine on my D4 was running very rough. It barely had enough power to turn the Diesel engine. I talked with a guy about possibly rebuilding and he suggested starting with the cheapest options first. Spark plugs and wires. I couldn't find the right wire anywhere. I finally just went to the local Peterson Cat store and ordered them. They were a little more expensive than I thought they would be at $57.
Since installing the plugs and wires engine alway starts within two pulls. 95% of the time it starts within one pull.
I have to admit I didn't know about the different wire types until reading this post.
I bet Dayton Tractor 509-382-4824 has what you need.