Here an example, how it could be build using BC547 transistors and 10k resistors.
Use the photos as guidance.
It is encouraged to use a 2x5 pinheader instead of soldering the female d-sub connector to the board. It has a smaller footprint and ensures that both connectors will find their counterpart on the home computer as the distance will differ between the systems.
Especially with the Atari ST, there is not much room under the keyboard.
Reduced to the essentials. The sense pins are only required for C1351 mode as the internal logic has to synchronize with the measurement cycle of the SID.
The whole circuit
