You can run a psu up to 35 volts and get more torque and not damage the control board. Obviously, the one you have is 26V, and they’re a little hard to find with a specific voltage and the right connector. Its easier to find one and swap the connectors.
I’ve refit for high torque steppers on my machine, but they require higher voltage to generate more torque, when I did that I also replaced essentially the entire carbide control board mechanism. I have an article in the forum on the whole process. I’m very happy with it. I will say that most of the grbl boards out there are junk - anything less than $20 or so is a knock off of a really nice design with crappy parts, and no support for current grbl. You want this one: ($20) Arduino CNC Shield – 100% GRBL Compatable | Protoneer.co.nz with a real arduino uno r3. The carbide board is actually very good, it’s foibles are minor.