Engine sputtering/stalling when in reverse?

I have the vehicle listed above with a Slant 6 motor. Whenever I shift into reverse, the motor begins to sputter intermittently and eventually stalls out. However, if I press the gas while in reverse, I do not have this issue, but this is obviously not always possible when backing into a parking space, adjusting parking, etc. Is there anything I can adjust on the carburetor and/or motor to prevent this from happening?

I have attached a brief video for reference along with photos of the engine and carburetor.