The generator matrix

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

generates a code of length 28 over GR(64,4) who´s minimum homogenous weight is 160.

Homogenous weight enumerator: w(x)=1x^0+350x^160+1582x^168+2968x^176+4032x^184+28672x^189+6055x^192+200704x^197+7518x^200+6412x^208+3220x^216+630x^224

The gray image is a code over GF(8) with n=224, k=6 and d=160.
This code was found by Heurico 1.16 in 14.6 seconds.