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

generates a code of length 58 over GR(64,4) who´s minimum homogenous weight is 376.

Homogenous weight enumerator: w(x)=1x^0+175x^376+112x^380+168x^381+504x^383+2177x^384+560x^387+2632x^388+3136x^389+2352x^391+7084x^392+2800x^395+11592x^396+8400x^397+6048x^399+12173x^400+10640x^403+32984x^404+23296x^405+11088x^407+23800x^408+14672x^411+38696x^412+22344x^413+8680x^415+15050x^416+322x^424+301x^432+189x^440+98x^448+70x^456

The gray image is a code over GF(8) with n=464, k=6 and d=376.
This code was found by Heurico 1.16 in 13.7 seconds.