The generator matrix

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

generates a code of length 58 over GR(64,4) who´s minimum homogenous weight is 389.

Homogenous weight enumerator: w(x)=1x^0+2128x^389+6720x^390+4200x^391+147x^392+168x^393+1008x^394+2800x^395+5824x^396+12824x^397+21280x^398+12656x^399+966x^400+1008x^401+3360x^402+5600x^403+7168x^404+18144x^405+30464x^406+18536x^407+2856x^408+2408x^409+6384x^410+9520x^411+12096x^412+24248x^413+34720x^414+14784x^415+49x^416+35x^424+21x^432+7x^440+7x^448+7x^456

The gray image is a code over GF(8) with n=464, k=6 and d=389.
This code was found by Heurico 1.16 in 11.3 seconds.