Just for fun, I've decided to try my hand at a custom pump handle for this project. The challenge is going to be those 10-32 threads. I stopped at Lowes today to see if they have any threaded inserts, but they didn't have what I needed. I may try adding a hidden groove for a nut and grinding down the excess. I see a few good options for inserts online.
The 3D model can be seen here: https://a360.co/2PfLvY1