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

generates a code of length 50 over GR(64,4) who´s minimum homogenous weight is 320.

Homogenous weight enumerator: w(x)=1x^0+84x^320+595x^328+812x^336+3584x^343+623x^344+25088x^351+483x^352+553x^360+420x^368+217x^376+210x^384+84x^392+14x^400

The gray image is a code over GF(8) with n=400, k=5 and d=320.
This code was found by Heurico 1.16 in 0.505 seconds.