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

generates a code of length 84 over F8[X]/(X^2) who´s minimum homogenous weight is 576.

Homogenous weight enumerator: w(x)=1x^0+2156x^576+9408x^580+4333x^584+2688x^588+1743x^592+9408x^596+2975x^600+56x^608

The gray image is a linear code over GF(8) with n=672, k=5 and d=576.
This code was found by Heurico 1.16 in 0.391 seconds.