The generator matrix

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

generates a code of length 12 over GR(64,4) who´s minimum homogenous weight is 56.

Homogenous weight enumerator: w(x)=1x^0+378x^56+1687x^64+3332x^72+9828x^80+229376x^84+10850x^88+6692x^96

The gray image is a code over GF(8) with n=96, k=6 and d=56.
This code was found by Heurico 1.16 in 3.35 seconds.