A bit further research on the Husky A-1 with published VY that is within one knot of the A-1B, and VX should be very similar.
https://www.aviator.at/pics/husky/Ch..._Husky_A-1.pdf
However the A-1 published VX numbers are 58 MPH at sea level and 60.5 MPH at 10000 ft. The engine powering the A-1B is generally the same O-360-A1P as the A-1A so the climb speeds should be generally the same also.
Thus the most likely explanation is that it is indeed a typo in the A-1B AFM and the correct numbers are probably 57 MPH at sea level and 60 MPH at 10000 ft, instead of 67 and 70.