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

generates a code of length 46 over GR(64,4) who´s minimum homogenous weight is 280.

Homogenous weight enumerator: w(x)=1x^0+336x^280+1526x^288+2527x^296+3199x^304+4221x^312+5131x^320+229376x^322+5320x^328+5019x^336+3633x^344+1372x^352+427x^360+56x^368

The gray image is a code over GF(8) with n=368, k=6 and d=280.
This code was found by Heurico 1.16 in 27.6 seconds.