For a spring-mass system undergoing simple harmonic motion, the maximum velocity is given by:
\[
v_{\text{max}} = A \omega
\]
where \( A \) is the amplitude, and \( \omega \) is the angular frequency. The angular frequency \( \omega \) is related to the spring constant and mass by:
\[
\omega = \sqrt{\frac{k}{m}}
\]
Given that the amplitudes of both bodies are equal, we can write the ratio of the maximum velocities for bodies A and B as:
\[
\frac{v_A}{v_B} = \frac{A \omega_A}{A \omega_B} = \frac{\omega_A}{\omega_B} = \sqrt{\frac{k_1}{k_2}}
\]
Thus, the ratio of the maximum velocity of A to that of B is \( \sqrt{\frac{k_1}{k_2}} \).