The generator matrix

 1  0  0  1  1  1  X  1  1  X  1  0  0  1  1  1  0  1  1  0  1  1  0  0  1  1  0  0  X  X  X  X  0  X  X  0  1  1  0  1  1  X  1  1  0  1  1  X  X  X  0  1  1  1  1  1  0  X  1  1  X  1  1  0  X  X  1  0  1  X  1
 0  1  0  0  1 X+1  1  0  1  1 X+1  1  0  0  X X+1  1  X X+1  1  X  1  1  X  X  1  1  X  1  1  1  1  1  1  1  1  0 X+1  1  0 X+1  1  X  1  1  X  1  1  0  0  X  X  0  X  X  0  0  0  0  X  X  0  X  0  0  X  0  X  X  1  1
 0  0  1  1  1  0  1  X X+1 X+1  X  X  1 X+1  X X+1 X+1  0  1  1  1  X  0  1 X+1  0  X  1  1 X+1  1  1 X+1 X+1 X+1  1  0  0  0  X  X  X  X  X  X  0  0  0  0  X  X  1  1  1 X+1  X  1  1  0  1  0  0 X+1  1  1  X  X  X  1  X  1
 0  0  0  X  0  0  0  0  0  0  0  0  0  X  X  X  X  X  X  X  0  X  X  X  0  X  X  X  0  0  X  X  0  X  X  0  0  0  X  X  X  0  X  X  0  0  0  X  X  0  0  0  0  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  0
 0  0  0  0  X  X  0  X  0  X  0  X  X  X  X  0  0  0  X  X  0  0  0  0  X  X  X  X  X  0  X  0  X  0  X  0  X  0  X  0  X  0  0  X  0  X  0  X  0  X  X  X  0  X  0  X  0  0  X  0  0  0  X  X  X  0  0  0  X  X  X

generates a code of length 71 over Z2[X]/(X^2) who´s minimum homogenous weight is 68.

Homogenous weight enumerator: w(x)=1x^0+96x^68+74x^70+36x^72+16x^74+13x^76+1x^80+10x^84+6x^86+2x^88+1x^92

The gray image is a linear code over GF(2) with n=142, k=8 and d=68.
As d=68 is an upper bound for linear (142,8,2)-codes, this code is optimal over Z2[X]/(X^2) for dimension 8.
This code was found by Heurico 1.16 in 0.154 seconds.