The generator matrix

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

generates a code of length 71 over GR(64,4) who´s minimum homogenous weight is 481.

Homogenous weight enumerator: w(x)=1x^0+6384x^481+10528x^482+7504x^483+336x^485+105x^488+24752x^489+27272x^490+14728x^491+1120x^493+203x^496+31696x^497+30800x^498+15232x^499+2128x^501+196x^504+37520x^505+35336x^506+16296x^507+7x^536

The gray image is a code over GF(8) with n=568, k=6 and d=481.
This code was found by Heurico 1.16 in 14.1 seconds.