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

generates a code of length 48 over GR(64,4) who´s minimum homogenous weight is 312.

Homogenous weight enumerator: w(x)=1x^0+826x^312+1008x^313+112x^315+224x^316+5334x^320+4648x^321+896x^322+2352x^323+2016x^324+10059x^328+12264x^329+12544x^330+16464x^331+9632x^332+24164x^336+22008x^337+43904x^338+38416x^339+16800x^340+19985x^344+17416x^345+420x^352+301x^360+252x^368+77x^376+21x^384

The gray image is a code over GF(8) with n=384, k=6 and d=312.
This code was found by Heurico 1.16 in 10.8 seconds.