I built a similar thing, primarily for my own fun. As a reaction to various C64 tools being scattered/old/unsupported exes and often with not OSX builds, my approach was to build a low-friction web app, which I could mess around with easily across whatever machine I was sitting in front of, whenever I had a few moments (kids...)
Examples : https://46c.io/project/NVXAZ7JY/code/ram/0E2B https://46c.io/project/8VM2EY7T/library
Basically : select a byte (or a range with shift) and use the buttons at the top to tag it with some metadata like a label, a comment, mark it as the lo/hi byte of a pointer etc - and it'll update the disassembly immediately. It saves all your work in browser local storage by default but if you sign in you can work from 'the cloud' (cheapo Firebase account) - I haven't shared widely before so no idea how that will hold up to the HN effect...
Enjoy!
Using my similar tool [0], I feel I get roughly a 100x speedup. I will definitely try regenerator2000.
(Edit): you kids have it easy.
I was working on a project to do ECU performance curve remapping for a rally driver friend, so mine had additional features like the ability to export memory segments as .m files for plotting curves in Matlab.
I watched a video about ECU remapping (on a modern processor) yesterday, and the guy started by using the OBD port to get access to the system. I had to physically desolder the EPROM from the board to dump it back in the day.
The kids today have it far too easy.