PCBway community page for an adapter for a Commodore 1541-series disk drive. Makes it possible to add a parallel interface port to the drive for the purposes of disk ripping. Rather than cutting traces and soldering directly to a 6522 chip, it fits in between the chip and its socket. Add some ribbon cable and a DB-15 plug and there you go.
The picture is a helpful reference for how the IC socket and header bars are positioned.
Note that, per the response to my question:
Pins 9 and 10 are connected to pins 18 and 39 of 6522 - CB0 and CA1 (some count it from 1 so it's CB1 and CA2 then). They are needed only when drive is connected with C64 via userport to handshake while sending data. You don't need those for XUM1541/ZoomFloppy.
A suite of open source electronic design tools. Uses a GUI for schematic capture. Also capable of analog and digital simulation, generation of parts lists and export of PCB designs for fabrication.
A website which lets you design circuitry online in your web browser (i.e., without having to (buy, download and install PCB engineering software). The online circuit designer contains a library of known, documented, and trusted subassemblies of circuits (like power supplies, amplifiers, and volume controls) that you can use as the framework of your circuit, but you have to add the rest. They plan on making it possible to automatically generate and e-mail all of the files a third party small-run manufacturer would need to etch, drill, and mail your circuit boards to you.