Just takes time and awkward arm and hand movements.
Determine the size once you remove it. Probably a Wilwood 7/8 master but the Best way to tell is to remove it and see. Different cars use a variety of sizes. Especially if the previous owner had to swap it out. Cost for the replacement kit is around $70. Everyone sells them online. Here's one from speedway. I think this is the one I replaced mine with. Been a few years.
Wilwood Combination Remote Fill Master Cylinder Kit