The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  2  1  1  1  1  1
 0  2  0  0  0  2  2  2 2a  0  2 2a 2a 2a 2a  0  2 2a^2+2 2a^2+2a 2a^2 2a+2  0
 0  0  2  0  0 2a^2+2 2a^2+2a+2 2a^2+2a 2a^2+2a  2 2a+2 2a^2+2  0  2 2a^2+2a+2 2a 2a+2  0 2a^2+2a 2a^2 2a^2  0
 0  0  0  2  0  2 2a^2+2a+2 2a 2a+2 2a^2 2a^2+2  0 2a^2+2a+2  2 2a 2a^2+2a 2a+2 2a^2 2a+2 2a^2 2a  2
 0  0  0  0  2 2a^2+2 2a+2 2a 2a^2+2a+2 2a 2a^2 2a^2 2a+2  0 2a  2 2a^2 2a^2+2a  0 2a^2+2a+2 2a^2+2a 2a^2+2

generates a code of length 22 over GR(64,4) who´s minimum homogenous weight is 120.

Homogenous weight enumerator: w(x)=1x^0+301x^120+1645x^128+2730x^136+4641x^144+28672x^147+7721x^152+200704x^155+8736x^160+5264x^168+1729x^176

The gray image is a code over GF(8) with n=176, k=6 and d=120.
This code was found by Heurico 1.16 in 10.4 seconds.