I was in a similar situation last October. Cylinder had a steady leak and after tear down a deep scratch. I bought the aftermarket cylinder, the NAA piston and I am satisfied with the results. As you stated I did need to grind the scallop per Tim Daley"s write up. It took all of ten minutes and that"s with me working very slowly and deliberately. I also needed to touch up one of the bolt hole surfaces so the bolt head would sit flush on the cylinder. The cylinders are pretty thick and not as tapered as the originals. All in all not a big deal. Here are some of my references.
The How to Repair Economically by Tim Daley and the Hydraulic Troubleshooting from Zane Sherman.