The generator matrix

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

generates a code of length 48 over GR(64,4) who´s minimum homogenous weight is 296.

Homogenous weight enumerator: w(x)=1x^0+609x^296+2030x^304+2737x^312+448x^315+3395x^320+9408x^323+4340x^328+65856x^331+4935x^336+153664x^339+5432x^344+4809x^352+2723x^360+1463x^368+287x^376+7x^384

The gray image is a code over GF(8) with n=384, k=6 and d=296.
This code was found by Heurico 1.16 in 28.6 seconds.