Your could bore and thread the brake to 5/8-18 and thread the barrel to suit. Or get a brake with a 5/8-18 thread, thread the barrel to match.
Or you could turn the barrel and thread it 1/2-28 and install the brake that you have.
Best practice is to set the barrel up in the lathe, centered on the bore. Do the threading. Install the brake. Bore the brake to the proper diameter while it is on the barrel. This way, the bore and brake will be truly coaxial.
If the barrel were mine, I would thread it for 5/8, and install a matching brake.
I assume that the Holland brake you have is for an AR, if it was made with 1/2-28 threads.