The generator matrix

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

generates a code of length 26 over GR(64,4) who´s minimum homogenous weight is 144.

Homogenous weight enumerator: w(x)=1x^0+273x^144+1260x^152+2520x^160+7133x^168+55671x^176+182910x^184+7413x^192+3913x^200+1050x^208

The gray image is a code over GF(8) with n=208, k=6 and d=144.
This code was found by Heurico 1.16 in 12.9 seconds.