The generator matrix

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

generates a code of length 15 over GR(64,4) who´s minimum homogenous weight is 88.

Homogenous weight enumerator: w(x)=1x^0+651x^88+581x^96+966x^104+28672x^105+1386x^112+511x^120

The gray image is a code over GF(8) with n=120, k=5 and d=88.
This code was found by Heurico 1.16 in 10.8 seconds.