The generator matrix

 1  0  0  1  1  1  1  1
 0  1  0  1  a a^2 3a+3 a^2+3a
 0  0  1 a^2+2a+1  a 3a^2+3a+2  1 a^2+3a+3

generates a code of length 8 over GR(64,4) who´s minimum homogenous weight is 42.

Homogenous weight enumerator: w(x)=1x^0+1568x^42+196x^48+7168x^49+21952x^50+104048x^56+50176x^57+76832x^58+203x^64

The gray image is a code over GF(8) with n=64, k=6 and d=42.
This code was found by Heurico 1.16 in 0.518 seconds.