The generator matrix

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

generates a code of length 39 over GR(64,4) who´s minimum homogenous weight is 248.

Homogenous weight enumerator: w(x)=1x^0+259x^248+840x^253+2184x^255+2695x^256+896x^259+8232x^261+6888x^263+4410x^264+12544x^267+38360x^269+22680x^271+12705x^272+43904x^275+67256x^277+25592x^279+11592x^280+518x^288+322x^296+217x^304+49x^312

The gray image is a code over GF(8) with n=312, k=6 and d=248.
This code was found by Heurico 1.16 in 8.54 seconds.