The generator matrix

 1  0  0  0  1  1  1  0  1  4  1  1  6  1  2  2  6  1  1  1  1  1  4  1  6  1  2  4  4  1  0  1  2  2  1  2  1  1  1  1  1  1  2  1  1  0  0  6  1  1  1  2  1  1  1  1  6  4  1  1  4  1  6  1
 0  1  0  0  0  4  4  4  1  1  7  3  1  5  1  4  1  7  2  1  3  0  1  6  1  2  6  1  2  2  1  7  1  1  5  6  6  5  2  0  3  5  6  0  4  1  2  2  4  5  1  1  4  2  0  3  1  1  4  7  1  5  1  4
 0  0  1  0  4  1  5  1  5  1  3  0  2  2  5  2  4  7  6  3  2  7  7  4  2  5  1  5  1  3  1  6  3  4  7  0  3  6  0  2  5  4  1  5  7  3  1  2  2  3  1  7  7  5  6  5  1  2  1  5  2  1  5  4
 0  0  0  1  7  7  0  3  4  0  5  6  7  7  7  1  6  4  6  1  0  2  2  1  1  7  4  1  7  0  6  2  0  1  6  1  3  5  6  4  3  2  2  5  4  7  0  1  6  7  1  5  3  5  7  2  2  3  2  4  5  6  4  0

generates a code of length 64 over Z8 who´s minimum homogenous weight is 58.

Homogenous weight enumerator: w(x)=1x^0+152x^58+270x^59+389x^60+402x^61+531x^62+322x^63+387x^64+284x^65+358x^66+226x^67+220x^68+138x^69+135x^70+78x^71+77x^72+56x^73+40x^74+16x^75+13x^76+1x^80

The gray image is a code over GF(2) with n=256, k=12 and d=116.
This code was found by Heurico 1.16 in 0.569 seconds.