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  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  X  1  1  1
 0  X  0  0  0  X  X  X a*X  0  X a*X a*X a*X a*X  X a*X a^5*X  0  X  0 a^4*X a^2*X a^4*X a^2*X a^3*X a^2*X a^6*X  X a^2*X a*X  0 a^4*X  0 a^2*X a^3*X a^4*X a^2*X a^4*X a^4*X a^2*X a^2*X a^5*X a^3*X a^6*X a^6*X  0 a^6*X a^6*X  X  X  0 a^3*X  X  0 a^6*X  X a^2*X a^6*X a^4*X  X a^3*X  X  0
 0  0  X  0  0 a^6*X a^5*X a^4*X a^4*X  X a^3*X a^6*X  0  X a^5*X a^2*X a*X a^6*X a*X  0 a^2*X a*X a^5*X a^2*X a^3*X a^4*X a^3*X a^5*X a^6*X a^2*X a^6*X a*X a^6*X a^2*X  0 a^5*X a^5*X a^3*X a^6*X a^3*X a^2*X a^2*X  0  0  0 a^5*X a^4*X a*X a^3*X  X a^3*X a^6*X a^2*X  0 a^6*X a^3*X  0 a^5*X a*X a^5*X a^4*X  X a^3*X  0
 0  0  0  X  0  X a^5*X a*X a^3*X a^2*X a^6*X  0 a^5*X  X a*X a^4*X a^4*X a^4*X a^4*X a*X  X  0  X  X a^5*X a^5*X a*X  0  X  X a^2*X  X  0 a^6*X a^6*X a^6*X  X a^4*X a^5*X a*X a^4*X a^2*X a^4*X a^3*X  0 a^5*X a*X  X a^6*X a^3*X a^2*X  0 a^5*X a^2*X a^2*X a*X a*X a*X  X  0 a*X  X a*X a*X
 0  0  0  0  X a^6*X a^3*X a*X a^5*X a*X a^2*X a^2*X a^3*X  0 a*X  0 a^2*X a^4*X  X a^3*X a^4*X a*X a^3*X  0 a^6*X a^4*X  X  0 a^2*X  0 a^4*X  X  X a^6*X a*X a^3*X a^3*X a^2*X a^3*X a*X  0 a^5*X a^3*X  X a^4*X a^2*X  X a^3*X a^4*X  0 a^6*X  0 a^5*X a*X a^4*X a^2*X a^5*X  0 a^6*X a^2*X a^2*X a*X a^4*X a*X

generates a code of length 64 over F8[X]/(X^2) who´s minimum homogenous weight is 400.

Homogenous weight enumerator: w(x)=1x^0+189x^400+1267x^408+2135x^416+2926x^424+3297x^432+3969x^440+28672x^441+4333x^448+200704x^449+4396x^456+4137x^464+3094x^472+1974x^480+784x^488+231x^496+28x^504+7x^512

The gray image is a linear code over GF(8) with n=512, k=6 and d=400.
This code was found by Heurico 1.16 in 40.2 seconds.