The generator matrix

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

generates a code of length 91 over GR(64,4) who´s minimum homogenous weight is 608.

Homogenous weight enumerator: w(x)=1x^0+322x^608+448x^614+4536x^615+3269x^616+2632x^622+19600x^623+7567x^624+5544x^630+34944x^631+14091x^632+11480x^638+68208x^639+21574x^640+8568x^646+44744x^647+13762x^648+266x^656+147x^664+126x^672+70x^680+70x^688+105x^696+35x^704+21x^712+7x^720+7x^728

The gray image is a code over GF(8) with n=728, k=6 and d=608.
This code was found by Heurico 1.16 in 23.2 seconds.