Have you ever seen The Driveway Engineer on YouTube? He did something similar with a Ford 9.75 rear axle and swapped it in his 1979 Chevrolet C10. He had a machine shop redrill the stud holes to fit GM wheels and welded new shock mounts and leaf spring perches on the axle to fit his truck.
If I wasn't having a shop swap my axle rn and if I had a welder, I'd consider this. However, I know that K2XX (2014-2018/19) trucks have a GM version of a 9.75 rear axle. If they didn't cost so much money, I'd also consider this as well.
Right now I'm having a shop swap a 14 bolt 9.5in SF non Gov Lock rear axle in for my 10 bolt 8.5 inch that rotted away. After 2 10 bolts rot away I was done with these rear axles and wanted something better. I know that a 14b SF is what everyone does, but it seems like these rear axles never go bad so it would be the most logical way to go.