Beavertail jigs usually come in 2 flavors, Ed Brown and Wilson/Caspian. So depending on which style you like best that's the one you buy.
I've only ever done 2 slide jobs. In both cases I very carefully squeezed them in a vise and then used lapping compound to smooth them out. Neither one would be ' match ' grade or tight. Just enough to take the excess slop out. Your choice of tooling there will depend on how serious you plan on taking your build.
At worst just call the Brownells tech support hotline. They're great to deal with and they can guide you to the right products for your needs.