See below the wiring connections from the C64 keyboard to the C16 wiring and how I connected mine.
C64 - C16
Brown/white trace - Purple
Red/white trace - Green
Orange/white trace - Brown
Yellow/white trace - Red
Green/white trace - Grey/white trace
Orange - Purple/white trace
Yellow - Black
Green - Blue
Blue - Yellow
Lavender - Orange
Grey - Yellow/white trace
Black - Brown/white trace
White - Grey
Brown - Orange/white trace
Red - Blue/white trace
Blue/white trace - White
Lavender/white trace - Green/white trace
Grey/white trace - Red/white trace
1. Cut keyboard cable from dead C64 keyboard
2. Desoldered keyboard connector from dead C64
3. Soldered the cut wires to the keyboard connector matching the wires as indicated above
4. Plugged original C16 keyboard connector onto the C64 connector