The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1  1  1  1  1  1  1  1
 0  1  1  a 3a^2+2 2a^2+3a+1 a^2+3a a^2+3a+3 3a^2+2a+3  a 3a^2+2  0 2a^2+3 a^2+3a+3 a^2+3a 3a^2+2a+3 2a^2+3a+1  1 2a^2+3 a^2+3a+3 2a^2+3a+1  a 3a^2+2 a+2 a^2+3a+1 a^2+3a 2a^2+3a+3 2a^2+3 a^2+a a^2+a+3 a^2+a+1 2a^2+3a+3  0 3a^2+2a+2 2a^2+3a+3  2 2a  1 a+3 3a^2+2a+2 2a^2+a 2a^2 a^2+a 3a^2+2a 3a^2+2a+3 2a^2+2 2a^2+a+1 3a^2+3 2a^2+3a+1  0
 0  0 2a^2+2  0  2  2 2a+2  2 2a^2 2a+2 2a^2+2 2a^2 2a^2  0  0 2a^2 2a^2+2  2  2 2a 2a+2 2a^2+2a 2a+2 2a^2+2  0 2a^2+2a+2 2a^2+2a 2a^2+2a 2a 2a^2+2 2a^2+2 2a+2 2a^2  0 2a^2+2a 2a 2a 2a^2 2a^2+2a  0 2a^2+2a+2 2a 2a^2+2a+2 2a 2a+2 2a+2 2a^2+2a+2 2a 2a^2+2  0
 0  0  0  2 2a^2+2 2a^2+2a+2 2a+2 2a^2 2a^2+2a+2 2a^2+2 2a^2+2 2a^2+2a 2a 2a^2 2a^2+2a+2  0 2a^2+2a 2a^2+2a+2 2a 2a+2  0 2a^2+2a  2 2a+2 2a 2a^2+2a+2  2 2a+2 2a^2 2a  0 2a^2+2 2a^2+2  0 2a  2 2a 2a+2 2a^2+2a+2 2a^2+2a 2a 2a^2+2 2a^2+2a  0  2 2a+2  0 2a^2+2a+2 2a+2  2

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

Homogenous weight enumerator: w(x)=1x^0+70x^320+168x^326+448x^327+609x^328+56x^329+448x^330+1064x^331+2128x^332+2296x^334+2632x^335+791x^336+1176x^337+4032x^338+5768x^339+7056x^340+4648x^342+5544x^343+658x^344+8232x^345+19264x^346+21112x^347+22512x^348+11816x^350+11480x^351+532x^352+19208x^353+33600x^354+29400x^355+25648x^356+9744x^358+8568x^359+497x^360+357x^368+280x^376+203x^384+84x^392+14x^400

The gray image is a code over GF(8) with n=400, k=6 and d=320.
This code was found by Heurico 1.16 in 11.5 seconds.