The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1  0  1  1  1  1  1  1  1  1  1  X  1  1  1  1  1  1  1  X  1  1  1  1  1  1  1  1  1 a^6*X  1  1  1  X  1  1  1  1  1 a^5*X a^6*X  1 a^7*X  1  1  1  1  1  1  1  1  1  1 a*X  1  1  1  1  1  1  1
 0  1  1  a a^7*X+a^2 a^3 a^7*X+2 a^7*X+a^6 a^5 a^7  0 a^7 a^5  a a^7*X+a^6 a^7*X+1 a^7*X+a^2 a^3  1 a^7*X+2  0 a^7*X+1 a^7*X+a^6 a^3  1  a a^7*X+2 a^7*X+a^2 a^5 a^7  X a^6*X+a^6 X+a^7 a^6*X+2  1 a^7*X+1 X+a X+a^3 a^6*X+1 X+a^5 a^6*X+a^2 X+a^5  1 a*X+a^3 a^2*X+a^7 a^2*X+a^5 a^6*X+a^6 a^6*X+a^6 a^5*X+a^2 a^2*X+1 a^5*X+2 X+a^5  1 a*X+a  X a^2*X+a^7  1 a^6*X+a^2 a^5*X+a^6 a^2*X+a a^2*X+a^7 X+a^6  1  1 2*X+a  1 a^2*X+a^6 a^5*X a^7*X+a^6 X+a a*X+a X+a a*X a^5*X+a^2 a^6*X+1 a^3*X+a^6  1 2*X+1 a^5*X+a^6 a*X+a a*X+a^5 a^7*X+a^2 a^5*X+a^2 a^3
 0  0 a^7*X  0 a^7*X  X a^6*X a^6*X 2*X a*X a^7*X a*X  X  0 a^5*X a^3*X a^6*X 2*X a^5*X a*X a^5*X 2*X a*X a^3*X a^5*X a^2*X a^7*X  0 2*X  X a^5*X a^5*X a^3*X  0 a^3*X a^2*X a*X 2*X a^2*X  0 a^3*X a^5*X a*X  X  X a^5*X a^6*X  X  X a^7*X a*X a*X a^3*X a*X a^7*X 2*X a*X a^2*X 2*X  0 a*X  0 a^5*X a*X a^5*X a^2*X a^2*X a^2*X a^7*X a^7*X a^3*X 2*X a^3*X a^7*X a^3*X a^5*X  0 2*X a^2*X a^3*X  0 a^7*X a^6*X a*X
 0  0  0  X a^7*X a^7*X  X a*X  X a^2*X a^5*X a^6*X a^5*X a*X a^2*X a^7*X  0 a^3*X a*X a^3*X a^6*X 2*X a*X a^5*X  X  0  X a^7*X a^6*X a*X a*X 2*X a*X a^6*X  0 a^2*X  X a^6*X a^7*X  X  0 a^3*X a^7*X  0 a^5*X a^5*X a^2*X  X a^6*X 2*X a^6*X a^7*X a^7*X a^2*X a*X a^2*X a^6*X a^6*X  X a^5*X  0 2*X  0  X  0  X 2*X a^3*X a^3*X  X  0 a^5*X a^5*X 2*X a*X a^6*X a^2*X a^5*X a^7*X a^7*X 2*X  0  X a^6*X

generates a code of length 84 over F9[X]/(X^2) who´s minimum homogenous weight is 639.

Homogenous weight enumerator: w(x)=1x^0+592x^639+216x^642+72x^643+288x^644+432x^645+2664x^647+3048x^648+720x^650+1152x^651+4464x^652+6408x^653+3888x^654+11736x^656+7128x^657+4320x^659+4968x^660+13392x^661+15336x^662+9072x^663+20088x^665+13168x^666+18360x^668+20736x^669+41184x^670+42264x^671+20952x^672+42264x^674+20112x^675+29088x^677+25416x^678+45864x^679+40680x^680+18144x^681+28224x^683+13432x^684+376x^693+360x^702+384x^711+264x^720+120x^729+32x^738+24x^747+8x^756

The gray image is a linear code over GF(9) with n=756, k=6 and d=639.
This code was found by Heurico 1.16 in 48.7 seconds.