The generator matrix

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

generates a code of length 7 over GR(64,4) who´s minimum homogenous weight is 40.

Homogenous weight enumerator: w(x)=1x^0+147x^40+147x^48+3584x^49+217x^56

The gray image is a code over GF(8) with n=56, k=4 and d=40.
This code was found by Heurico 1.16 in 0.000565 seconds.