Focus FK-5001 that I cleaned up and converted to USB. White Alps, original double-shot ABS caps. The calculator works.

EDIT: This fucker developed a short within like an hour of my closing the case back up. Now I have to either use my multi-meter to learn the entire 130-key matrix, or I have to desolder all the switches and kill the calculator function to turn the board into a hand-wired custom, though that would allow the left side function keys to be different from the top-row ones. Sigh.